Antibiogram of chronic ulcers from
\r\n\tTime limitations for making appropriate decisions for management and control lead to the implementation of autonomic functionalities as self-configuration, self-optimization, self-healing, self-protection in computer systems, transportation systems, distributed systems. This book aims to provide an insight into applications and solutions for the domains of modeling, simulation and optimization (MSO) which address time as important and expensive resource. Applications in the domains of information systems, transportation, logistics, decision making in financial investments, computer systems and control systems will also be included.
",isbn:null,printIsbn:"979-953-307-X-X",pdfIsbn:null,doi:null,price:0,priceEur:0,priceUsd:0,slug:null,numberOfPages:0,isOpenForSubmission:!1,hash:"61e17f9eb92862993a754497de016cf4",bookSignature:"Prof. Todor Stoilov",publishedDate:null,coverURL:"https://cdn.intechopen.com/books/images_new/9042.jpg",keywords:"Real Time Control, Automation, Optimization, Coordination, Resource Allocation, Task Scheduling, Time Planning, Decision Making, Business Management, Information Systems, Transport Systems, Computer Systems",numberOfDownloads:null,numberOfWosCitations:0,numberOfCrossrefCitations:0,numberOfDimensionsCitations:0,numberOfTotalCitations:0,isAvailableForWebshopOrdering:!0,dateEndFirstStepPublish:"September 11th 2019",dateEndSecondStepPublish:"October 2nd 2019",dateEndThirdStepPublish:"December 1st 2019",dateEndFourthStepPublish:"February 19th 2020",dateEndFifthStepPublish:"April 19th 2020",remainingDaysToSecondStep:"2 years",secondStepPassed:!0,currentStepOfPublishingProcess:5,editedByType:null,kuFlag:!1,biosketch:null,coeditorOneBiosketch:null,coeditorTwoBiosketch:null,coeditorThreeBiosketch:null,coeditorFourBiosketch:null,coeditorFiveBiosketch:null,editors:[{id:"51706",title:"Prof.",name:"Todor",middleName:null,surname:"Stoilov",slug:"todor-stoilov",fullName:"Todor Stoilov",profilePictureURL:"https://mts.intechopen.com/storage/users/51706/images/system/51706.jfif",biography:"Prof. Todor Stoilov is a researcher at the Institute of Information and Communication Technologies, affiliated to the Bulgarian Academy of Sciences. He graduated in 'Control engineering” in Technical University of Sofia. Prof. Todor Stoilov obtained his PhD in 1979; and in 1999 he obtained the highest scientific title - 'Doctor of Science”. Since 2000, he is a full professor in Bulgarian Academy of Sciences. He has published six monographs and more than 300 scientific papers and articles. His current research interests address domains like optimization, resource allocation, hierarchical control, management of information, transport, financial systems.",institutionString:"Bulgarian Academy of Sciences",position:null,outsideEditionCount:0,totalCites:0,totalAuthoredChapters:"3",totalChapterViews:"0",totalEditedBooks:"1",institution:{name:"Bulgarian Academy of Sciences",institutionURL:null,country:{name:"Bulgaria"}}}],coeditorOne:null,coeditorTwo:null,coeditorThree:null,coeditorFour:null,coeditorFive:null,topics:[{id:"23",title:"Social Sciences",slug:"social-sciences"}],chapters:null,productType:{id:"1",title:"Edited Volume",chapterContentType:"chapter",authoredCaption:"Edited by"},personalPublishingAssistant:{id:"305835",firstName:"Ketrin",lastName:"Polesak",middleName:null,title:"Mrs.",imageUrl:"https://mts.intechopen.com/storage/users/305835/images/9351_n.png",email:"ketrin@intechopen.com",biography:"As an Author Service Manager my responsibilities include monitoring and facilitating all publishing activities for authors and editors. From chapter submission and review, to approval and revision, copyediting and design, until final publication, I work closely with authors and editors to ensure a simple and easy publishing process. I maintain constant and effective communication with authors, editors and reviewers, which allows for a level of personal support that enables contributors to fully commit and concentrate on the chapters they are writing, editing, or reviewing. I assist authors in the preparation of their full chapter submissions and track important deadlines and ensure they are met. I help to coordinate internal processes such as linguistic review, and monitor the technical aspects of the process. As an ASM I am also involved in the acquisition of editors. Whether that be identifying an exceptional author and proposing an editorship collaboration, or contacting researchers who would like the opportunity to work with IntechOpen, I establish and help manage author and editor acquisition and contact."}},relatedBooks:[{type:"book",id:"1854",title:"Time Management",subtitle:null,isOpenForSubmission:!1,hash:"5a1635f5b500ab9fc005d3ed088b0c5a",slug:"time-management",bookSignature:"Todor Stoilov",coverURL:"https://cdn.intechopen.com/books/images_new/1854.jpg",editedByType:"Edited by",editors:[{id:"51706",title:"Prof.",name:"Todor",surname:"Stoilov",slug:"todor-stoilov",fullName:"Todor Stoilov"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"6942",title:"Global Social Work",subtitle:"Cutting Edge Issues and Critical Reflections",isOpenForSubmission:!1,hash:"222c8a66edfc7a4a6537af7565bcb3de",slug:"global-social-work-cutting-edge-issues-and-critical-reflections",bookSignature:"Bala Raju Nikku",coverURL:"https://cdn.intechopen.com/books/images_new/6942.jpg",editedByType:"Edited by",editors:[{id:"263576",title:"Dr.",name:"Bala",surname:"Nikku",slug:"bala-nikku",fullName:"Bala Nikku"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"1591",title:"Infrared Spectroscopy",subtitle:"Materials Science, Engineering and Technology",isOpenForSubmission:!1,hash:"99b4b7b71a8caeb693ed762b40b017f4",slug:"infrared-spectroscopy-materials-science-engineering-and-technology",bookSignature:"Theophile Theophanides",coverURL:"https://cdn.intechopen.com/books/images_new/1591.jpg",editedByType:"Edited by",editors:[{id:"37194",title:"Dr.",name:"Theophanides",surname:"Theophile",slug:"theophanides-theophile",fullName:"Theophanides Theophile"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"3161",title:"Frontiers in Guided Wave Optics and Optoelectronics",subtitle:null,isOpenForSubmission:!1,hash:"deb44e9c99f82bbce1083abea743146c",slug:"frontiers-in-guided-wave-optics-and-optoelectronics",bookSignature:"Bishnu Pal",coverURL:"https://cdn.intechopen.com/books/images_new/3161.jpg",editedByType:"Edited by",editors:[{id:"4782",title:"Prof.",name:"Bishnu",surname:"Pal",slug:"bishnu-pal",fullName:"Bishnu Pal"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"3092",title:"Anopheles mosquitoes",subtitle:"New insights into malaria vectors",isOpenForSubmission:!1,hash:"c9e622485316d5e296288bf24d2b0d64",slug:"anopheles-mosquitoes-new-insights-into-malaria-vectors",bookSignature:"Sylvie Manguin",coverURL:"https://cdn.intechopen.com/books/images_new/3092.jpg",editedByType:"Edited by",editors:[{id:"50017",title:"Prof.",name:"Sylvie",surname:"Manguin",slug:"sylvie-manguin",fullName:"Sylvie Manguin"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"371",title:"Abiotic Stress in Plants",subtitle:"Mechanisms and Adaptations",isOpenForSubmission:!1,hash:"588466f487e307619849d72389178a74",slug:"abiotic-stress-in-plants-mechanisms-and-adaptations",bookSignature:"Arun Shanker and B. Venkateswarlu",coverURL:"https://cdn.intechopen.com/books/images_new/371.jpg",editedByType:"Edited by",editors:[{id:"58592",title:"Dr.",name:"Arun",surname:"Shanker",slug:"arun-shanker",fullName:"Arun Shanker"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"72",title:"Ionic Liquids",subtitle:"Theory, Properties, New Approaches",isOpenForSubmission:!1,hash:"d94ffa3cfa10505e3b1d676d46fcd3f5",slug:"ionic-liquids-theory-properties-new-approaches",bookSignature:"Alexander Kokorin",coverURL:"https://cdn.intechopen.com/books/images_new/72.jpg",editedByType:"Edited by",editors:[{id:"19816",title:"Prof.",name:"Alexander",surname:"Kokorin",slug:"alexander-kokorin",fullName:"Alexander Kokorin"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"314",title:"Regenerative Medicine and Tissue Engineering",subtitle:"Cells and Biomaterials",isOpenForSubmission:!1,hash:"bb67e80e480c86bb8315458012d65686",slug:"regenerative-medicine-and-tissue-engineering-cells-and-biomaterials",bookSignature:"Daniel Eberli",coverURL:"https://cdn.intechopen.com/books/images_new/314.jpg",editedByType:"Edited by",editors:[{id:"6495",title:"Dr.",name:"Daniel",surname:"Eberli",slug:"daniel-eberli",fullName:"Daniel Eberli"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"57",title:"Physics and Applications of Graphene",subtitle:"Experiments",isOpenForSubmission:!1,hash:"0e6622a71cf4f02f45bfdd5691e1189a",slug:"physics-and-applications-of-graphene-experiments",bookSignature:"Sergey Mikhailov",coverURL:"https://cdn.intechopen.com/books/images_new/57.jpg",editedByType:"Edited by",editors:[{id:"16042",title:"Dr.",name:"Sergey",surname:"Mikhailov",slug:"sergey-mikhailov",fullName:"Sergey Mikhailov"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"1373",title:"Ionic Liquids",subtitle:"Applications and Perspectives",isOpenForSubmission:!1,hash:"5e9ae5ae9167cde4b344e499a792c41c",slug:"ionic-liquids-applications-and-perspectives",bookSignature:"Alexander Kokorin",coverURL:"https://cdn.intechopen.com/books/images_new/1373.jpg",editedByType:"Edited by",editors:[{id:"19816",title:"Prof.",name:"Alexander",surname:"Kokorin",slug:"alexander-kokorin",fullName:"Alexander Kokorin"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}}]},chapter:{item:{type:"chapter",id:"53022",title:"Antimicrobial Activity of Chitosan Membranes Against Staphylococcus Aureus of Clinical Origin",doi:"10.5772/65980",slug:"antimicrobial-activity-of-chitosan-membranes-against-staphylococcus-aureus-of-clinical-origin",body:'\nChitosan is a cationic linear polysaccharide composed of glucosamine and N-acetyl glucosamine units linked by β (1-4) glucoside bonds [3]. This polymer is biodegradable and has antimicrobial activity against
The skin surface is characterized by a slightly acidic pH that favors the development of some bacteria [6]. However, in an open wound, within the first 24–48 h can be found
Skin infections affect the epidermis, subcutaneous tissue, and muscle. Some of them require hospital admission for antimicrobial or surgical treatment. Depending on their severity, they have been associated with increased hospital stays and medical costs because traditional antibiotic treatments require long periods [8]. An alternative to antibiotics is curing materials with bioactive components. These dressings should ideally maintain a moist environment, act as antimicrobials to prevent secondary infections, remove exudate, and promote tissue regeneration [9, 10] One group evaluated the antimicrobial action of cotton textile impregnated with chitosan against bacteria isolated from the skin and found that chitosans of low- and high-molecular weight showed effective inhibition of
Chitosan was obtained by thermo-alkaline hydrolysis of chitin, which was recovered by lactic fermentation of shrimp waste. The chitin was demineralized (0.1 M HCl at 25°C for 4 h) and deproteinized (4.5% NaOH at 65°C for 4 h). Afterward, purified chitin was deacetylated (40% NaOH at 110°C for 2 h) to obtain chitosan, according to reported methodologies [13]. Chitosan was washed until a neutral pH was reached and dried at 50°C. The purity of the chitosan was verified based on its moisture and ash content by method given in reference [14].
\nDegree of deacetylation of chitosan was determined by a spectrophotometric method reported by Liu et al. [15]. Briefly, two standard solutions were prepared; D-glucosamine (7.49 mM) and N-acetylglucosamine (0.49 mM), from these, working solutions were prepared to obtain a 12-point line of different concentrations. The absorbance of the standard solutions and samples were read at 201 nm in a UV-Vis spectrophotometer (Genesys 10 UV, Madison, IA, USA). Finally, the degree of deacetylation was calculated with the following equation, %DD = (161.1 ×
The molecular weight of chitosan was determined as proposed by Solis et al. [16], based on the intrinsic viscosity, according to Mark-Houwink´s equation
Chitosan was identified by Fourier Transform Infrared Spectroscopy (FTIR) according to the methodology given in reference [17], with some modifications. The spectral resolution was of 4 cm−1 with 64 scans in a range of 600–4000 cm−1 using a Thermo Scientific (Nicolet5s, Madison, IA, USA) infrared spectrometer.
\nSix chitosan based formulations using 1% acetic acid were prepared. Three pure chitosan solutions (1, 2, and 3%), another of 2% chitosan with glycerin (five drops per 100 ml) and two more solutions of 2% chitosan using honey (95:5, v/v) with and without glycerin. For the last two solutions, honey was diluted in distilled water (80:20, v/v) and homogenized by stirring.
\nAll chitosan membranes were prepared by solvent evaporation. For this, solutions of each formulation were poured into polypropylene plates (10 ml in each mold) and dried at 40°C for 24 h in an oven (Felisa, Zapopan, Jalisco, Mexico). Lastly, the films were removed from the mold and stored in sterile plastic bags until use.
\nBetween June and December 2015, a descriptive and cross-sectional study was conducted in order to evaluate the effect of chitosan membranes against
The samples were obtained from the center of the ulcer by a medical epidemiologist. For this, a Stuart medium swab collection system (COPAN Transystem, Brescia, Italy) was used. The labeled samples were transported in a container to a certified microbiology laboratory for processing within the same hour.
\nFor microbial isolation and identification, the samples were inoculated by cross-streaking on MacConkey agar for Gram-negative bacterium and trypticase soy agar (TSA) for culture collection. Mannitol salt agar was used for Gram-positive bacterium and Biggy agar for fungi inoculated by streaking. Next, the plates were incubated at 37°C for bacteria and 30°C for fungi for 24 h. Later, macroscopic characteristics of colony-forming units (CFU) were analyzed.
\nFor the identification of microorganisms, a broth microdilution method was used, with an inoculation Prompt™ system precision wand. Isolated colonies were emulsified in Prompt™ innoculation bottles for an equivalent concentration of 0.08 with the McFarland standard. Next, 100 μl per well were deposited in the SIEMENS microplates from a MicroScan RENOK panel which was incubated at 37°C for 24 h. Specifically, type 33 plates (B1017-211) were used for Gram-positive bacteria and type 44 (B1017-305) for Gram-negative bacteria. Later, each plate was read for the identification of studied microorganisms using a LabPro Command Center software. Antibiotic sensitivity was performed simultaneously with phenotypic identification using a RENOK MicroScan panel. The MIC (Minimum Inhibitory Concentration) was determined according to the CLSI (Clinical and Laboratory Standards Institute) criteria for each antibiotic. The studied antibiotics were oxacillin, gentamicin, tetracycline, daptomycin, ampicillin, erythromycin, penicillin, nitrofurantoin, vancomycin, levofloxacin, moxifloxacin, ciprofloxacin, linezolid, ceftriaxone, Sinercid, clindamycin, rifampin, amoxicillin/clavulanate k, trimethoprim/sulfamethoxazole, and ampicillin/sulbactam.
\nThe sensitivity test for
Chitosan based membranes were cut into 16 mm diameter discs and placed in triplicate on the inoculated agar with sterile forceps, ensuring direct contact between both surfaces. Each agar also included two blank controls that consisted of Whatman # 1 paper; one was impregnated with 1% acetic acid and the other with 0.9% sodium chloride. Plates were incubated at 37°C for 24 h. Lastly, the antimicrobial effect of chitosan was evident by observing the existence of inhibition zones below the membranes and inhibition halos around each membrane.
\nThe ash content of chitosan is an indication of its purity. For chitosan with 9.42 ± 0.07% moisture, the average ash contents are 0.37 ± 0.02%. The range of ash content is 0.08% for langoustine obtained chitosan [19] and 4.0% to crab obtained chitosan [20], whereas for chitosan obtained from shrimp, the range is from 0.070 [21] to 0.832% [22]. Variations in ash content are due to the location of origin, as well as the purification and thermos-alkaline hydrolysis of chitin.
\nThe molecular weight of chitosan determines its functional properties and its antimicrobial activity. This study found that the average molecular weight of chitosan was 119.48 kDa, estimated based on the intrinsic viscosity. With this value, chitosan can be classified as a low molecular weight (50–190 kDa) material. Therefore, the molecular weight is a reflection of the process conditions used to obtain chitosan from the purification and thermo-alkaline deacetylation of chitin. Other investigations have reported molecular weights for shrimp obtained chitosan of 136 [23], 180 [24], and 1260 kDa [25]. While the values reported for chitosan obtained from crab shells vary from 1240 [26] to 483 kDa [27]. For fungal chitosan, reports show low molecular weight, from 41 [24] to 110–150 kDa [25]. Davoodbasha et al. [28] conducted antimicrobial tests with commercial chitosan 100–300 kDa. Hernández-Ochoa et al. [29] also studied the antimicrobial activity of commercial chitosan with different molecular weight (low: 50–190 kDa, medium: 190–310 kDa and high: 310–375 kDa) finding satisfactory results with the lower molecular weight.
\nFor the degree of deacetylation of chitosan, an average value of 84.59 ± 0.87% (
The FTIR technique made it possible to identify the functional groups in the chitosan molecule (Figure 1). At 881.96 cm−1, a characteristic band of the stretching of the glycosidic bond can be observed; also at 1055.62 and 1028.60 cm−1 the stretching of C─O can be seen. It is possible to observe the bending band N─H of the primary amide formed during deacetylation at 1545.72 cm−1 and the amine group at 1626.76 cm−1. At the position of 2884.84 cm −1 the stretching of C─H and at 2962.02 cm−1 the tense vibration from group C─H can be observed. Ultimately, OH and N─H were identified at 3274.61 and 3359.51 cm−1, respectively. These results are similar to those reports given by references [32, 34]. As reported by Shigemasa et al. [35], errors in band intensity can occurred at positions 1640 and 3450 cm−1 due to the effect of water absorption.
\nFTIR spectra of powdered chitosan.
Dissolved chitosan is capable of forming a membrane due to the evaporation of the solvent, as well as forming intra and intermolecular hydrogen bonds between the chitosan polymer chains [36]. Chitosan membranes were prepared using pure chitosan and a mix of chitosan with glycerin or honey. All membranes were transparent, uniform, and smooth at the surface and with hard texture when chitosan concentration was increased. Pure chitosan membranes show a very pale yellow color and membranes containing honey show a brown tone. All membranes were easily removed from the polyethylene plates with 9.5 cm in diameter, and thickness depending on the concentration of chitosan, found in the range of 0.0131 ± 0.0021 and 0.0339 ± 0.0034 mm for 1 % and 3 %, respectively.
\nFrom patients hospitalized for various reasons in a regional hospital located in northwestern Mexico, 23 infected skin ulcers derived from toes, sacral parts, coccyx, arm, and leg stumps were analyzed. The age range of the patients was from 43 to 96 years. Among the isolated and identified strains were
Antibiogram | \nUD-001 | \nUD-002 | \nUD-020 | \nUD-021 | \nUD-023 | \nUD-024 | \nUD-025 | \nUD-029 | \nUD-030 | \n
---|---|---|---|---|---|---|---|---|---|
Oxacillin | \nR ˃2 | \nS < 0.25 | \nS < 0.25 | \nR ˃ 2 | \nR ˃ 2 | \nR ˃ 2 | \nR ˃ 2 | \nR ˃ 2 | \nR ˃ 2 | \n
Gentamicin | \nS < 4 | \nS < 4 | \nS < 4 | \nR ˃ 8 | \nR ˃ 8 | \nS < 4 | \nR ˃ 8 | \nS < 4 | \nS < 4 | \n
Tetracycline | \nS < 4 | \nS < 4 | \nS < 4 | \nR ˃ 8 | \nR ˃ 8 | \nR ˃ 8 | \nS < 4 | \nS < 4 | \nS < 4 | \n
Daptomycin | \nR ˃ 4 | \nR ˃4 | \nR ˃4 | \nR ˃ 4 | \nR ˃ 4 | \nR ˃ 4 | \nS < 0.5 | \nR ˃ 4 | \nS < 0.5 | \n
Ampicillin | \nR ˃ 8 | \nR ˃ 8 | \nS < 2 | \nR ˃ 8 | \nR ˃ 8 | \nR ˃ 8 | \nR ˃ 8 | \nR ˃ 8 | \nR ˃ 8 | \n
Erythromycin | \nR ˃ 4 | \nR ˃4 | \nR ˃4 | \nR ˃ 4 | \nR ˃ 4 | \nR ˃ 4 | \nR ˃ 4 | \nR ˃ 4 | \nR ˃ 4 | \n
Penicillin | \nS < 0.03 | \nR ˃ 8 | \nR ˃ 8 | \nR ˃ 8 | \nR ˃ 8 | \nR ˃ 8 | \nR ˃ 8 | \nR ˃ 8 | \nR ˃ 8 | \n
Nitrofurantoin | \nR ˃ 64 | \nS < 32 | \nS < 32 | \nS< 32 | \nR ˃ 64 | \nR ˃ 64 | \nS < 32 | \nS < 32 | \nS < 32 | \n
Vancomycin | \nS < 0.25 | \nS < 0.25 | \nR ˃ 16 | \nS < 0.25 | \nS < 32 | \nR ˃ 16 | \nR ˃ 16 | \nR ˃ 16 | \nR ˃ 16 | \n
Levofloxacin | \nR ˃ 4 | \nS < 1 | \nR ˃ 4 | \nR ˃ 4 | \nR ˃ 4 | \nR ˃ 4 | \nR ˃ 4 | \nR ˃ 4 | \nR ˃ 4 | \n
Moxifloxacin | \nR ˃ 4 | \nS < 0.5 | \nR ˃ 4 | \nR ˃ 4 | \nR ˃ 4 | \nR ˃ 4 | \nR ˃ 4 | \nR ˃ 4 | \nR ˃ 4 | \n
Ciprofloxacin | \nR ˃ 2 | \nS < 1 | \nR ˃ 4 | \nR ˃ 2 | \nR ˃ 2 | \nR ˃ 2 | \nR ˃ 2 | \nR ˃ 2 | \nR ˃ 2 | \n
Linezolid | \nS < 1 | \nS < 1 | \nR ˃ 4 | \nR ˃ 4 | \nR ˃ 4 | \nS < 1 | \nS < 1 | \nR ˃ 4 | \nR ˃ 4 | \n
Ceftriaxone | \nR ˃ 32 | \nS < 8 | \nS < 8 | \nS < 8 | \nR ˃ 32 | \nR ˃ 32 | \nR ˃ 32 | \nS < 8 | \nR ˃ 32 | \n
Synercid | \nS < 0.5 | \nS < 0.5 | \nR ˃ 2 | \nR ˃ 2 | \nR ˃ 2 | \nS < 0.5 | \nS < 0.5 | \nS < 0.5 | \nS < 0.5 | \n
Clindamycin | \nR ˃ 4 | \nS < 0.5 | \nS < 0.5 | \nR ˃ 4 | \nR ˃ 4 | \nR ˃ 4 | \nR ˃ 4 | \nR ˃ 4 | \nR ˃ 4 | \n
Rifampin | \nS < 1 | \nS < 1 | \nS < 1 | \nR ˃ 2 | \nR ˃ 2 | \nS < 1 | \nS < 1 | \nS < 1 | \nS < 1 | \n
Amoxicillin/K clauvulanato | \nR ˃ 4/2 | \nS < 4/2 | \nR ˃ 4/2 | \nR ˃ 4/2 | \nR ˃ 4/2 | \nR ˃ 4/2 | \nR ˃ 4/2 | \nR ˃ 4/2 | \nR ˃ 4/2 | \n
Trimethoprim/sulfamethoxazole | \nS < 0.5/9.5 | \nS < 0.5/9.5 | \nR ˃ 2/38 | \nR ˃ 2/38 | \nR ˃ 2/38 | \nS < 0.5/9.5 | \nR ˃ 2/38 | \nR ˃ 2/38 | \nS < 0.5/9.5 | \n
Ampicillin/sulbactam | \nR ˃ 16/8 | \nR ˃ 16/8 | \nS < 8/4 | \nR ˃ 16/8 | \nR ˃ 16/8 | \nS < 8/4 | \nS < 8/4 | \nS < 8/4 | \nS < 8/4 | \n
Antibiogram of chronic ulcers from
R, resistant; S, sensitive.
Table 1 shows the minimum inhibitory “
Figure 3 shows that most strains are resistant to the most commonly used antibiotics. All isolates were resistant to erythromycin. Only one of the nine strains showed sensitivity toward ampicillin, penicillin, levofloxacin, ciprofloxacin, and amoxicillin.
\nAntibiotic sensitivity and resistant toward
The most commonly used antibiotics for
The “
In a study by Hernández-Ochoa et al. [29], with
The antimicrobial properties of chitosan mainly depend on the degree of deacetylation and molecular weight, as well as pH and ionic strength of the medium [41]. El-tahlawy et al. [42] and Hosseinnejad and Jafari [43] reported that low molecular weight chitosan can penetrate into the cell and inhibits mRNA and protein synthesis. Chitosan oligomers have higher antimicrobial effect due to their shorter chain and free amino groups from D-glucosamine [44]. Similarly, Champer et al. [45] reported that the amount of free amino groups influence the antibacterial properties of chitosan. Likewise, Wang et al. [46] state that all bacteria possess negative charges; therefore, they are easily captured by the protonated amine groups of chitosan and lose their reproductive functions and bioactivity. Acetic acid has an effect on the solubility of the polymer and on the protonation of the amino groups.
\nKim et al. [47] evaluated the antimicrobial activity of chitosan membranes of different molecular weights with
Additionally, it was observed that the membranes tend to increase their diameter by staying in contact with the agar, thus increasing the antimicrobial effect by contact. Table 2 presents the increase in diameter and area of the membranes at the end of agar diffusion assay. For pure chitosan membranes, it was found that an increase in size is directly proportional to its concentration. It was also observed that the addition of glycerin or honey increases the size of the chitosan membranes by 2%. The 2% chitosan membranes mixed with honey and glycerin showed the greatest increase, however, bacterial growth was observed.
\nMembranes | \nIncreased radius (mm)a | \nIncrease in contact area (%)b | \n
---|---|---|
Qo 1% | \n9.01 ± 4.97 | \n20.03 ± 14.90 | \n
Qo 2% | \n9.39 ± 6.48 | \n30.61 ± 17.33 | \n
Qo 3% | \n9.70 ± 9.58 | \n39.80 ± 25.80 | \n
Qo 2% + gly | \n9.74 ± 6.34 | \n40.34 ± 17.38 | \n
Qo 2% + miel | \n11.20 ± 4.65 | \n65.38 ± 20.29 | \n
Qo 2% + miel + gly | \n11.20 ± 4.53 | \n88.32 ± 21.73 | \n
Comparison of the increase in radii and areas of chitosan membranes.
a8.25 mm initial radius.
b213.82 mm2 initial area.
Vlacha et al. [49] reported that free hydroxyl groups from chitosan interact with the moist atmosphere increasing the diameter of the membrane. Also, Zamora-Mora et al. [50] mentioned that pure chitosan membranes show a higher water holding capacity due to the hydrophilicity of the chitosan. According to Estrada et al. [51], honey potentiates the antimicrobial activity of chitosan due to chemical action of its components; hydrogen peroxide, organic acids and flavonoids, nectar, pollen, and propolis. For Grade et al. [52], plasticizers provide flexibility to the membranes, but weaken the intermolecular forces and cause the penetration of water through the membrane increasing its size [23].
\nDifferent types of chitosan-based membranes mixed with glycerol and honey were developed and characterized. These membranes showed antimicrobial activity against
AA Escárcega-Galaz gratefully acknowledges the Consejo Nacional de Ciencia y Tecnología (CONACYT) by PhD scholarship: 417707. This research was funded by the Instituto Tecnológico de Sonora (Project PROFAPI-00471) and by the Consejo Nacional de Ciencia y Tecnología (PDCPN2014: 248160).
\nSatellite control system (SCS) is a core, essential subsystem that provides to the satellite capabilities to control its orbit and attitude with a certain performance that is required for satellite mission and proper functioning of satellite payload operation. However, the first mandatory task for SCS is assuring satellite safe functionality; providing sufficient electric power, thermal and communication conditions to be able for nominal functioning during specified life time at different sun lightening conditions (including potential eclipse periods), protecting against life critical failures proving to satellite safe attitude in Safe Hold Mode (SHM). Without SCS or satellite guidance, navigation and control (GN&C) system, any Earth-orbiting satellite could be considered just as artificial space body, demonstrating the
The first human-made Earth-orbiting satellite (Soviet Sputnik), Simplest Satellite (SS-1), was launched on October 4, 1957. This satellite was launched following the development of the Soviet intercontinental ballistic rocket R-7 (8 K71). Nevertheless, it started a new era of space human exploration (Figure 1).
Soviet designers-creators of the first earth-orbiting artificial satellite SS-1.
SS-1 technical characteristics are as follows [4, 5]:
Mass 83.6 kg; sealed from two identical hemispheres with a diameter of 0.58 m; life time 3 months; payload, two 1 W transmitters (HF, 20.005 and VHF, 40.002 MHz) with four unidirectional deployable antennas (four 2.4–2.9 m metallic rods); electrical batteries, silver-zinc; sufficient for 2 weeks.
Orbit: perigee 215 km, apogee 939 km, period 96.2 min, eccentricity 0.05, inclination angle 65.10 deg.
Inside, the satellite sphere was filled by nitrogen, and the temperature was kept within 20–23 deg. C with automatic thermoregulation-ventilation system (thermometer-ventilator).
The satellite had no attitude control and was free rotated around its center of mass in orbit, keeping initial angular speed, provided by the separation pulse after the separation from the launch rocket. However, thanks to the four rod antennas that provided unidirectional radio transmission in the two-radio bends, HF and VHF, SS-1 evidently indicated its presence in space for all people over the world. Even amateur radio operators with amateur receivers could receive famous now signals: BIP, BIP, BIP…!! (Figure 2).
SS-1, assembled (left). Open two semispheres (right).
Since SS-1, about 8378 satellites were launched to year 2018 [6]. Early satellite launches were extraordinary events and demonstrated tremendous achievement of the launched state, the USSR (4 Oct. 1957, SS-1), the USA (31 Jan. 1958, Explorer 1) and Canada (29 Sep. 1962, Alouette, launched by Thor-Agena, a US two-stage rocket), but with time, satellite launches became ordinary and usually pursue a certain military or civil mission.
Among the civil missions (satellites), the following types can be determined as already conventional: navigation, communication, Earth observation, scientific, geophysics and geodetic, technology demonstration and developers training. These satellites are usually equipped with a kind of payload system(s) (radio/TV transmitter/transducer, radar, telescope or different scientific instrument, etc.) to perform certain dedicated space mission(s). For example, the first Canadian Earth observation satellite RADARSAT-1 (Nov 4, 1995–May 10, 2013; Figure 3) was equipped with a side-looking synthetic aperture radar (SAR) on board the International Space Station (November 1998, ISS; Figure 4) was installed a Canadian robotic arm for its assembling and maintenance.
The first Canadian earth observation satellite RADARSAT-1.
International Space Station (ISS).
According to the satellite altitude (h), their orbits can be classified as low-altitude (LEO), 200–2000 km; medium-altitude (MEO), 5000–20,000 km; and high-altitude (HEO), h > 20,000 km; according to eccentricity as: close to circular e < 0.01; elliptical 0.01 < e < 0.3; highly elliptical 0.3 < e < 0.8.
There are satellites with special type of orbit such as polar (i = 90 deg), equatorial geostationary (GEO, i = 0 and h = 35,800 km) and Sun-synchronous provide orbital precession equal to Sun annual rate (i depends on satellite period) (Figure 5).
Satellite orbit types (“tundra” and “Molniya” are Russian communication satellites in highly ecliptic orbits).
Miniaturized low-cost satellites are as follows: small satellites (100–500 kg), microsatellite (below 100 kg) and nanosatellite (below 10 kg).
A large diversity of satellites serving for different missions is in space now. A widespread point of vew is that all of them are transportation platforms delivering and carrying in orbit dedicated to the planned space mission payload system, like a VIP passenger. For example, it could be the postman for the postal horse carriage for many years ago. Namely, the satellite with its control system (SCS) provides to the payload all conditions required for the mission performance (orbit, attitude, power, pressure, temperature, radiation protection and communication with ground mission control center (MCC)). That is why from the mission integration point of view, the SCS can be seen as the space segment integration bases that set their development and operation process in corresponding order. In turn, SCS as satellite subsystem also can be reviled and established in satellite onboard equipment architecture, combining the group of subsystems that are dedicated to orbit and attitude determination and control tasks. It could be done rather from the System Engineering than from the commercial practice point of view and would significantly streamline satellite development order and the degree of responsibility of all the developers.
It should be mentioned that such group of aircraft equipment in aviation has been named as GN&C Avionics; hence, for space, it can be named as the
Today, for many satellites, GN&C onboard equipment can be presented by the following subsystems, performing related functions listed below:
Global Positioning System (GPS)—onboard satellite orbit and time determination
Propulsion system—orbit/attitude control system
Attitude Determination and Control System (ADCS)—satellite attitude determination and control
Integration of these subsystems can be named as
Onboard computer system (OBCS) or dedicated to AODCS electronic cards (plates) in Central Satellite Computer System (e.g., command and data handling computer (C&DH))
Sensors
Actuators
Basic AODCS architecture is presented in Figure 6.
Satellite AODCS system.
OBCS, onboard computer system; TLM, telemetry data and commands; PL, payload; PS, propulsion system; RW, inertia reaction wheels; MTR, magnetic torque rods; GPS, satellite navigation Global Positioning System; MAG, 3-axis magnetometer; SS, 2-axis Sun sensor; HS, horizontal plane sensor; ST, star tracker; RS, angular rate sensor; EP, electric power; TR, temperature regulation; VP, vacuumed protection; RP, radiation protection.
Depending on required reliability and life time, each component can be a single or redundant unit. Unlike airplanes, satellite is an inhabitant space vehicle that is operated from the ground. The operation is usually performed via a bidirectional telemetry radio link (TLM) in S-band (2.0–2.2 GHz). Payload data downlink radio link (unidirectional) is usually performed via X-band (7.25–7.75 GHz;). For both links, usually the same data protocol standards are applied Figure 7.
Satellite communications with ground stations.
Two subsystems can be allocated in AODCS architecture, namely, orbit determination and control subsystem (ODCS) and attitude determination and control subsystem (ADCS). Practically both subsystems are dynamically uncoupled; however, orbital control requires the satellite to have a certain attitude (as well as orbital knowledge itself), and attitude control requires orbit knowledge also. Hence, orbit (its knowledge) is essentially continuously required on satellite board where it is propagated by special orbit propagator (OP). Due to orbital perturbations (residual atmospheric drag, gravity and magnetic disturbances and solar pressure), satellite orbit changes over time and OP accumulates errors; its accuracy is degraded.
Before the application of satellite onboard GPS receivers, the satellite position and velocity were periodically determined on ground by the ground tracking radio stations (GS, dish antenna), and calculated on-ground orbital parameters were periodically uploaded to satellite OBCS to correct OP, to provide available accuracy. Now with GPS satellite, orbit can be calculated onboard autonomously, and OP can propagate data only during relatively short GPS outage periods. For some applications, orbital data uploaded from the ground still can be used, at least, for fusion with GPS-based OP.
For newly developed satellites with GPS, orbit maneuvers (correction, deorbiting, collision avoidance, special formation flying and orbit servicing missions) can be executed autonomously onboard at planned time or from ground operators using orbital knowledge and TLM commands to activate satellite orbit control thrusters.
Below AODCS components are presented to show their generic principles that can help for the system understanding and modeling. Generic design requirements are presented in [3]. Some design examples can be found in many sources, for example, [1, 9, 10, 11, 12].
AODCS sensors are designed to measure satellite orbital and attitude position and velocity. From the most general point of view, they can be considered as the vector measuring devices (VMD). The device can measure in space a physical vector
Vector
Satellite GPS SRG-10. Double redundant with a pair of zenith and nadir antennas.
Vector module and its orientation can be expressed as functions of its projections
It can be noted that measurement of referenced vectors can be used for the determination of satellite position or angular orientation. A minimum of three vectors is required to determine satellite position and two to determine its attitude. If more vectors are measured providing informational redundancy, then such statistical estimation methods as least square method (LSM) and Kalman filter (KF) can be applied. Satellite velocity and angular rate can be derived by the differentiation of its position and attitude applying a kind of filter recommended by the filtering and estimation theory [13, 14, 15]. It should also be noted that if vector orientation is measured for the position determination, then satellite attitude should be known and vice versa.
Especial autonomous satellite navigation system (sensor) is the inertial navigation system (INS/inertial measurement unit (IMU)). It can be used for the determination of satellite position, velocity, orientation and angular rate simultaneously. INS is based on measuring with linear accelerometers and angular rate sensors (“gyros”) the two vectors: satellite linear active acceleration
Today, satellite GPS can provide onboard accurate data about position, velocity and time [19] (Figure 9).
Accuracy: position, 15 m (
GPS receiver is a radio range measuring device that measures distance from the desired satellite to navigation satellite constellation (NAVSTAR, USA; GLONASS, Russia; and GALILEO, Europe) and computes its position and velocity. GPS measures the distance R (
A minimum of three navigation satellites should be simultaneously traced by the receiver to determine position and velocity. Then satellite position is the cross-point of three spherical surfaces of the position equation
where
The TRIAD method [10] is applied when two different vectors are measured. They usually can be any of the three pairs combined with the following three vectors: Earth magnetic induction vector
Let us assume that two different physical nature not collinear vectors
These unit vectors expressed at a given time by measured values in measured frame or body frame and reference values in a reference frame define two rotation matrixes,
where vectors
Rotation matrix
Three Euler angles of rotation, roll (
where
If a pair from the three vectors (B, S, r-write as vectors) is measured, then following VMD in the pair can be used: SS (Figure 10), HS (Figure 11) and MAG (Figure 12).
If more than two vectors are measured and available for attitude determination, then LSM-BATCH method [10] can be applied to use informational redundancy for increasing the stochastic estimation accuracy. This method basically can be applied for any set of VMD but is specifically convenient for the star tracker (ST), when some number (
S-vector sensor Bradford fine sun sensor, accuracy, 0.2 deg. (
r-vector sensor HS CMOS/SRAM-modular infrared horizon sensor, accuracy, 0.4 deg. (
B-vector sensor MAG TFM100-S, accuracy, 10mG (
Star direction R-vector measured sensor (optic and computer units). Advanced stellar compass, accuracy,
Let us consider the transformation of the referenced vector
where
If the ST is in the tracking mode keeping in its FOV some
where
Then subtracting from (8)
where
Transforming in (10) matrix product and taking into account random measurement errors, this equation can be represented in the following form:
where
Then this equation can be considered as a “standard” linear algebraic equation:
where,
If
where
Satellite angular rate
Measurement of satellite angular velocity
Measured angular velocity vector
where
Often, specifically for attitude stabilization (keeping or aka pointing) mode, satellite angular rate is estimated by using the so-called body rate estimator and is not measured directly by the RS. Indeed, using for attitude keeping mode small angles and linear approximation, we can simplify satellite attitude dynamics model [9] to three single-axis state equations and present it with the stochastic influences as follows:
where
The linear KF can be applied to synthesize the estimator for the optimal estimation of the vector angle
where
Matrix KF (16) is separated in three independent scalar channels for
It can be shown that in the considering case, the steady-state (
where
where
or in other words, the time constant is in inverse proportionality to the filterability index (in ¼ degree) and the specific damping coefficient is conventional for such a second-order unit 0.707 for each of the three channels.
As it can be seen from the consideration above, the use of directly measuring devices (e.g., ST and RS) for attitude and body rate determination has a disadvantage. The random noises are at the devices output, and they have to be filtered in the closed control loop of satellite attitude control that puts some constraints to choose the control law coefficients. However, using indirect body rate measurement, the state estimator (filter) unavoidably introduces additional phase delay in the control loop because of the consecutive inclusion of this filter in the control loop. To use the RS (gyro) and the integrator for body rate and attitude determination autonomously for a long time is not possible because of the accumulated attitude errors caused by the integration of the gyro drift. The following scheme (that is common in Aviation) can be considered as free from the disadvantages above. Let us assume that satellite attitude is determined in two ways: continuous integration of RS angular velocity (IMU) and using VMD, for example, ST. Then this ST is used to correct the attitude derived by the integration of RS output. The idea of MSU is shown in Figure 16.
Integration of multisensory sensor unit (MSU) single-axis channel.
In integrated IMU attitude (IMU = RS + integrator) as in Figure 14 above (three identical channels),
where
where KF coefficients
Satellite propulsion system [9, 10] is usually designed for satellite orbital and/or angular control. In the first case, PS is commanded from the ground OC by TLM commands in some cases when satellite orbit has to be changed (orbit correction, deorbiting, collision avoidance), in the second controlled automatically from onboard AODCS. It consists of such typical elements as orbital and attitude thrusters (number and installation scheme depending on certain application), propulsion tank with associated pipes, valves, regulators, and electronics. General principles of PS act independently of the type (ion thrusters (0.01–0.1 N), liquid propellant and solid motor (100–10,000 N), cold gas (1-3 N)).
Figure 15 illustrates the satellite control with PS thruster principles. The principle of the formation of the propulsion jet force can be presented by the following equation of variable mass body dynamics that from Russian sources, for example, [23], is known as Prof. I. Meshchersky’s equation:
where
Satellite control with PS thruster principles.
In Section 3.2.2.1.2, it is always
The expelled propulsion mass
where
Prof. I. Meshchersky (1859–1935).
K. Tsiolkovsky (1857–1935).
Discrete pulse modulation control is usually used to minimize the consumption of the propellant for attitude control [9]. Examples of the gas thruster and the tank are presented in Figures 20 and 21.
Cold gas GN-2 thruster, nominal thrust 3.6 N (230 psi), specific impulse 57 s.
60 liter propulsion gas tank.
where
where
Typically, three coils are used; the three-coil assembly usually takes the form of three perpendicular coils, because this setup equalizes the rotational symmetry of the fields which can be generated; no matter how the external field and the craft are placed with respect to each other, approximately the same torque can always be generated simply by using different amounts of current on the three different coils (Figure 22).
3D orthogonal magnetic torque rods.
It can be seen from Eq. (26) that MTR cannot generate the magnetic torque in the direction that is parallel to Earth magnetic field
However, the following approach can be used to find required vector
Another MTR control method is the so-called B-dot control [25].
where
As the result of (29) control, the satellite will reduce its body rate and is finally slow rotated along Earth’s geomagnetic field line (vector
If the redundancy is required, it is provided by additional (redundant) coil with the same core (Figure 23).
Magnetic torque rod SSTL MTR-30, magnetic moment,
Reaction wheels (RW), aka momentum exchange devices [9] or reaction-momentum wheels (RMW), have massive rotated rotor with big axial moment of inertia with respect to the axis of rotation. They are electrically controlled by the electric motors and the rotor is installed on the rotating motor shaft. The controlled voltage, applied to the control winding of the motor, controls its rotor angular speed. The product of the rotor angular acceleration
Three orthogonal reaction wheels (RW).
RW can generate control inertia torques
In general case, RW can be run around in some nominal angular speed
where
Then differentiating (31) in rotating with angular velocity satellite axis
where
where
Eq. (33) can be represented in the following form:
where
The torque
where
In the operator Laplace s-form (transfer function), Eq. (36) can be rewritten as follows:
where
It should be noted that sometimes the RW control loop is more sophisticated. Special integrators could be connected into the loop to memorize and compensate the dry friction torques acting in bearings. Some small nominal rotating speed can be set for all three RMW to eliminate the dry friction torque having a pike when the wheel speed is zero
However, more representative case is when
Indeed, if we put in (32) that
where
Reaction/momentum wheel HR-0610, torque,
Independently of sytem arhitecture; it is separate dedicated to AODCS computer, or a special AODCS card within central satellite C&DH computer, it is the integration element of AODCS [1, 11]. AODCS system may consist of the computer (computer card) itself (OBC) and auxiliary intercommunication electronic units (electronic cards) AEU carrying DC/DC electric power conversion and I/O (analog and digital) interface and commutation functions.
OBC can be divided into two parts: the hardware (HW, power convertor, processor, input/output [I/O] convertors, non-volatile and volatile memory) and the software (SW, operation system [OS] and vital or functional software [VS/FS]) (Figure 26).
Satellite OBCS, MAC-200 (C&DH unit with AODCS card) comprises of two OBC: Prime and redundant (cold reserve).
What makes the satellite OBC essentially different for the airplane OBC is that its SW can be uploaded and updated from the ground and during operation and scheduled maintenance. OS OBC includes generic computer programs: program of I/O interface, time schedule (dispatcher), embedded test, timer and standard mathematic functions. Satellite SW often is considered as satellite
VS can be separated in two parts, ODCS SW and ADCS SW. For both parts, I/O interface with sensors and actuators is determined in special interface control document(s) (ICD), describing type, certain connectors, and electrical parameters of the exchanging data. These data before using them for functional tasks are pre-processed in OBC with special algorithms.
This group of algorithms performs the following common tasks:
Convert data into required physical parameters and units, taking into account certain sensor input–output scale function.
Transform data in certain device frame and compensate device misalignment, bias and scale function errors if it is possible, monitor device state, establishing “on/off,” “work/control,” “data bad/good” flags.
Transfer to C&DH TLM data about sensor/actuator state and their data.
Perform some other auxiliary functions if they are required.
Main functional tasks ODCS SW and ADCS SW can be listed as below.
To understand the idea of propagation of satellite orbit in Earth gravity field to the simplest, Keplerian motion propagator based on spherical Earth gravity field model might be used [9]; however more realistic results can be obtained with more accurate propagator, taking into account the second zonal harmonic
where
These equations can propagate satellite position and velocity (
where
Satellite orbit in the inertial ECI (XYZ) coordinate system.
If orbit maneuver is required, then it can be commanded by AODCS SW autonomously, or special control commands TLM (uploaded command tables) are sending to satellite AODCS, and in predetermined time they are executed activating at scheduled time for the calculated period
This group of algorithms was presented above in 3.2.1.2 and can be used here.
For example, let us consider single-axis stabilized satellite that should keep one axis (e.g.,
Satellite pointed by the Z-axis to the sun.
In Figure 28,
The following formula represents the mathematical transformation of the Sun vector from the reference into the body frame:
where
Then from (41), (42) can derive the following formulas:
From (43), desired angles and can be derived that can be used for satellite attitude control.
Let us also assume that the satellite does not have angular velocity sensors RS and its angular velocities should be derived from the measured angles
where
If not the optimization criterion to characterize the control quality [13] is required, then conventional negative feedback closed control loop with linear PID (proportional, integral, and damping) control law [9] that provides a good performance for many practical satellite control applications can be used to satisfy the requirements. They are typical for any automatic control system requirements: such as transfer process decay time and overshooting, residual static error caused by the permanent external disturbance, etc. Today, attitude control system performance can be verified mainly on ground with simulation. If we try to evaluate it in flight, then only onboard attitude sensors TLM data can be used for postprocessing, and it should be taken into account that mainly sensors that detect high-frequency noise (perceived errors) will be observable and low-frequency components (sensor biases) are compensated in the closed control attitude stabilization loop. Simple example of single-axis satellite attitude stabilization control loop is presented below. It is a simplified linear model; however, it presents the stabilization principle and essential features. Let us assume that a simple, positional, and damping control law is used to stabilize satellite axis
where
where
where
Let us take a ball-shaped satellite with the inertia matrix as follows:
where
Let us divide all terms in Eq. (50) by the coefficient
where
As it follows from Eq. (52), steady-state error in attitude stabilization can be calculated with the formula:
where
For Eq. (52),
Let us evaluate satellite time constant
and MTR has the following parameters: maximal magnetic moment
For the data above, it has the value of
as for a homogeneous sphere. Substituting into Eq. (55) the data above, we can calculate that for SS-1
Now damping coefficient can be calculated with the following formula:
It has the following value:
Finally,
When
Eqs. (51) and (52) were simulated using Simulink (see Figure 29).
Satellite single-axis attitude control Simulink block scheme.
Blocks in the pink color present the satellite model, the dark green color is for control law blocks, the cyan blocks are registration oscilloscopes, and the display and the orange color are the disturbances. The red manual switch allows to implement the differentiating filter, transforming the scheme from the approximation (52) to the accurate presentation (51). Disturbing external torque
Response to initial deviation angle
Response to initial angular velocity
Response to external disturbance torque
Response to attitude sensor bias
Satellite attitude measured errors ALPm.
Simulation of ACS (Figure 29) is presented in Figures 30–34. Units: vertical axis (deg), horizontal axis: (s).
Decay time:
As it can be seen, measured noise is filtered effectively in the control loop, and stabilization error is equal to the sensor bias with opposite sign.
In Figure 34, we can see that the measured (perceived) errors that TLM data provide to ground after the decay time do not present sensor bias and present only measured noise. It is because satellite stabilization error with opposite sign compensates the bias. In general, it can also be seen that the simulation of the approximate second-order model (52) is very close to the accurate model (51). Hence, at least for the analytical representation, (52) can be successfully used.
Part I of this chapter presents an overview of practical satellite control system, satellite guidance, navigation and control equipment. The work presented here is based on the author’s point of view of integration of this GN&C equipment in the integrated AODCS system (satellite GN&C Spacetronics System). Main work principles, architecture, and components of the satellite control system were briefly highlighted.
The chapter can serve to a wide pool of space system specialists as an introduction to satellite control system development.
The author wishes to express his sincere gratitude to the Canadian Space Agency, where he had the opportunity to learn and possess the knowledge and experience related to the writing of this chapter. As well, he is very thankful to many of his colleagues from Canadian Magellan Aerospace Company (Bristol Aerospace Division) with whom he discussed and analyzed satellite AODCS design projects and issues that helped him to work out the system analysis and its principal concepts presented in this chapter. Additionally, he cannot forget that his experience and background in Aerospace Technology were also accumulated from the former USSR (Moscow Aviation Institute, Moscow Aviapribor Corporation, Moscow Experimental Design Bureau Mars, Institute in Problems in Mechanic of RAN) and Israel (IAI, Lahav Division and Tashan Engineering Center), where he could observe and learn from diverse and wealthy engineering and scientific schools led by great scientists and designers such as Prof. BA. Riabov, Prof. V.P. Seleznev, V.A. Yakovlev, G. I. Chesnokov, V.V. Smirnov, Dr. A. Syrov, Acad. F. Chernousko, A. Sadot and Dr. I. Soroka.
This chapter was written as a solo author since his friend and regular coauthor Prof. George Vukovich from York University of Toronto passed away 2 years ago. For many years, Prof. Vukovich served as Director of his Department of Spacecraft Engineering in CSA. He will always keep good memories of Prof. Vukovich who helped and encouraged him continue his scientific and engineering work.
The author also acknowledges the copyrights of all publishers of the illustrations that were extracted from the open sources in the Internet.
Dedicated to Prof. G. Vukovich.
IntechOpen offers several publishing options to researchers and research groups looking for a professional partner with a wide, international reach. Our publishing options cover the breadth of scientific publications and ensure an appropriate outlet for your research.
",metaTitle:"Why publish with IntechOpen?",metaDescription:"IntechOpen offers publishing options to researchers and research groups looking for a professional partner with a wide, international reach. Our publishing options cover the breadth of scientific publications and ensure an appropriate outlet for your research.",metaKeywords:null,canonicalURL:"/page/why-publish-with-intechopen",contentRaw:'[{"type":"htmlEditorComponent","content":"