The induction motor,which converts electrical energy into mechanical energy,has been recognized as the cornerstone of industrialization.The rotor of an induction motor can be either a squirrel cage rotor or a wound-ty...The induction motor,which converts electrical energy into mechanical energy,has been recognized as the cornerstone of industrialization.The rotor of an induction motor can be either a squirrel cage rotor or a wound-type rotor,both existing as magnetless topologies.Three-phase squirrel cage induction motors are frequently utilized in industrial drives because they are dependable,have high starting torque,are selfstarting and affordable.Single-phase induction motors,on the other hand,are commonly used for small loads such as domestic appliances in form of modest fans,pumps and electric power tools.In South Africa,there have been reports of fires and explosions resulting in live and property loss because of induction motors that have not been thoroughly tested or are incorrectly labelled in terms of ratings,electrical safety and performance.The goal of this study is targeted at preventing end-user injuries and failures caused by non-compliant induction motors,by evaluating locally manufactured/imported induction motors based on tests and evaluation from standards(IEC and SANS).The study is conducted using experimental procedures at the Explosion Prevention Technology and Rotating Machines(EPT and RM)laboratory,South African Bureau of Standards(SABS),South Africa.The main finding from the study shows differences in the nameplate characteristics of various induction motors which could have detrimental effects such as production and operational downtime in their end-use industries,at later stages.展开更多
The symposium on inspection and testing bodies in the special action on standards comparison and complianee of 10,000 enterprises of 1,000 sectors in 100 cities was held in Beijing on April 16,which was attended by mo...The symposium on inspection and testing bodies in the special action on standards comparison and complianee of 10,000 enterprises of 1,000 sectors in 100 cities was held in Beijing on April 16,which was attended by more than 70 representatives from SAMR and inspection and testing bodies.展开更多
China is the biggest country of rice production and consumption in the world;more than 50% of the population feeds chiefly on rice. The quality of rice and its role as a staplefood carry much weight. The rice qualitie...China is the biggest country of rice production and consumption in the world;more than 50% of the population feeds chiefly on rice. The quality of rice and its role as a staplefood carry much weight. The rice qualities are those aspects concerning processing, appearance,cooking, nutrition and safety of the product. The study, formulation and implementation of standardson rice qualities and testing bear heavily on the improving of rice qualities, human health,substitution of rice varieties, promoting quality rice production and regulating rice market.展开更多
Based on the analysis of food testing standards (according to parameters, categories and methods), this paper puts forward an integrated reference method for food testing standards. At the same time, the innovation of...Based on the analysis of food testing standards (according to parameters, categories and methods), this paper puts forward an integrated reference method for food testing standards. At the same time, the innovation of food testing methods puts forward some "normal" requirements from aspects of coverage, recovery rate and consistency with determination standards.展开更多
As science and technology continue to develop,power equipment has become an indispensable part of industrial production and daily life.Whether it is the precise automation machinery utilized on production lines or the...As science and technology continue to develop,power equipment has become an indispensable part of industrial production and daily life.Whether it is the precise automation machinery utilized on production lines or the convenient electrical appliances found in households,their functionality relies heavily on electrical technology.Nonetheless,without stringent safety and performance assurances,these devices could potentially endanger lives and property.Thus,this paper explores the development strategy for establishing a standardized system within the electrical testing service industry,aiming to ensure safety and reliability.展开更多
The World Health Organization （WHO） standard assay for determining antibody level is the rapid fluorescent focus inhibition test （RFFIT） and is used to determine the degree of immunity after vaccination against ra...The World Health Organization （WHO） standard assay for determining antibody level is the rapid fluorescent focus inhibition test （RFFIT） and is used to determine the degree of immunity after vaccination against rabies. To compare the difference in RFFIT results between the laboratories of The National Institute of Infectious Disease in Japan （NIID） and the Chinese Centre for Disease Control （CCDC） as well the influence of the choice of standard serum （STD） for the detection, the two laboratories detection methods were simultaneously manipulated by RFFIT. The reference serums used in NIID and the WHO standard serum used in CCDC were compared in the same RFFIT detection to determine the titer of four sera samples C1, Sl, S2 and S4 in parallel, and the titers of the detected sera samples were calculated using the standard formula for neutralizing antibody titer. No significant difference was found in RFFIT methods from the two laboratories and the RFFIT testing procedures of the two laboratories have good consistency. However, different titers were obtained with the tentative internal standard serum （TI-STD） produced by adjusting to 2.0 IU of WHO standard serum in NIID and the WHO STD. The titer determined with the TI-STD was higher than that determined with WHO STD, This difference appears to be significant and requires further investigation展开更多
This article introduces the composition and working principle of home appliance control board automation testing equipment,elaborates on the importance of key technical indicators,explains the integrated design of fun...This article introduces the composition and working principle of home appliance control board automation testing equipment,elaborates on the importance of key technical indicators,explains the integrated design of functional modules,signal processing modules,and data analysis modules,and covers aspects such as the application of machine learning algorithms and the establishment of fault waveform databases.Finally,it looks forward to the development of intelligent testing systems and emphasizes the importance of building a standardized testing system.展开更多
The purpose of this study is to evaluate the price and composition of blood glucose meters and blood glucose test papers in Hubei Province,so as to improve the affordability of blood glucose monitoring for diabetes pa...The purpose of this study is to evaluate the price and composition of blood glucose meters and blood glucose test papers in Hubei Province,so as to improve the affordability of blood glucose monitoring for diabetes patients.Using the standard survey method jointly developed by the World Health Organization(WHO)and Health Action International(HAI)for drug price composition analysis,central level data was collected through literature review,policy review,and interviews with key informants.Field research was conducted in Wuhan and Yichang to trace price data at various levels of the supply chain.At the central level,data shows that China has implemented multiple policies related to the management and pricing of blood glucose meters and test strips,but has not yet introduced price restrictions for blood glucose meters and test strips;At the supply chain level,data shows that the price composition of blood glucose meters and test strips in Hubei Province is mainly composed of manufacturer prices and retail markups,followed by supply chain taxes and wholesale markups.It can be seen from this that China has established a comprehensive medical device registration,sales,quality control and management standard system through a series of policies.At present,China has not issued price policies for blood glucose meters and blood glucose test papers.Therefore,we can reduce product prices by including medical insurance,government subsidies,competitive bidding,and reducing supply chain taxes,thus improving the affordability of blood glucose monitoring for diabetes patients.展开更多
There are a few standards reported in the literature for testing and evaluation of thermal performance of solar concentrators based on sensible heating of working fluid. The preceding standard measures only the cookin...There are a few standards reported in the literature for testing and evaluation of thermal performance of solar concentrators based on sensible heating of working fluid. The preceding standard measures only the cooking efficiency and cooking capacity. Apart from thermal efficiency, there is an imperative need for other important parameters of the solar concentrators such as its stagnation temperature, cooking capacity, cost per watts delivered, weight of the cooker, ease of handling and aesthetics. The characterization of a concentrator at its operating temperature settles appropriate size and type of concentrator for any thermal application. The performance test is conducted at Chandwad (20.3292°N, 74.2444°E), Maharashtra and the proposed protocol aims for evaluation of thermal performance of solar cooking system and standardization of reporting the test results so that anyone can easily recognize and use it.展开更多
The objective of this work was to study the use of standard equipment in amplitude and frequency tests of dental scaler tip according to ISO 18397.Four types of standard equipment:a laser displacement sensor,a microsc...The objective of this work was to study the use of standard equipment in amplitude and frequency tests of dental scaler tip according to ISO 18397.Four types of standard equipment:a laser displacement sensor,a microscope,a tachometer,and an ultrasonic frequency meter,were experimentally investigated to test a tip.The standard laser displacement sensor and the standard microscope were used to test the unloaded amplitude of the scaler tip.It was found that two types of standard equipment were able to measure the unloaded amplitude of the tip.The standard microscope was also employed for the loaded amplitude test.This test was performed by pressing the scaler tip with a load of 1 N,which was measured by a load cell set.The peak-to-peak amplitude found from the test was 116.7 m.The frequency test of the scaler tip was conducted using the standard laser displacement sensor,the tachometer and the ultrasonic frequency meter.All three types of standard equipment were found to be able to test the frequency of the tip without cooling liquid.Nevertheless,only the standard tachometer was capable of measuring the frequency of the tip with cooling liquid applied.展开更多
A comprehensive overview of standardized testing system for ESL （English as a Second Language） students in U.S kindergarten thru grade 12 public school system is reviewed within the context of basis on federal and s...A comprehensive overview of standardized testing system for ESL （English as a Second Language） students in U.S kindergarten thru grade 12 public school system is reviewed within the context of basis on federal and state laws, as well as instructional basis. Identification process of LEP （Limited English Proficient） students via nomination, testing and testing criteria to be identified as LEP, hence ESL if placed in the program is defined in detail Standardized testing process of these students based on the federal AYP （Adequate Yearly Progress） measures through regular state standardized tests depending on three types of instructional program that LEP student is placed in the school that are Bilingual Education Program, ESL Program, and Two-Way Immersion Dual Language Programs are described. Standardized testing process of these students based on the federal AYP measures through other means if exempted from regular state standardized tests such as LAT （Linguistically Accommodated Testing） and the conditions to be exempted are discussed in detail. Holistically rated English Language Proficiency Assessments that are implemented to fulfill federal AMAOs （Annual Measurable Achievement Objectives） measures are defined briefly. Physical features of LAT test as well as direct and indirect accommodations for LAT reading, mathematics and science tests are defined via the accommodation needed and the type of assistance provided. Lastly, testing criteria to exit LEP status and other issues concerning exiting LEP status are reviewed展开更多
This paper introduces the common technical problems in the assembly process of gate valve, globe valve and swing check valve, analyzes the causes, and according to different reasons, gives the solutions and measures f...This paper introduces the common technical problems in the assembly process of gate valve, globe valve and swing check valve, analyzes the causes, and according to different reasons, gives the solutions and measures for the field assembly of valves. This paper introduces the pressure test inspection requirements of gate valves, globe valves and swing check valves and the determination of leakage methods. Introduce the common domestic and foreign standards for valve pressure test and leakage inspection.展开更多
[Objective] This research aimed at exploring an effective way for inoculation and identification of chrysanthemum white rust under controlled conditions. [Method] By combining the observation methods with the naked ey...[Objective] This research aimed at exploring an effective way for inoculation and identification of chrysanthemum white rust under controlled conditions. [Method] By combining the observation methods with the naked eye and under optical microscope, we had established the identification standards for chrysanthemum white rust with six classifications and optimized artificial inoculation methods in vitro. [Result] The results showed that bottled cuttings identification method and petri dished leaves identification method both can be used for identification in vitro of chrysanthemum white rust, bottled cuttings identification method had shown better effects than petri dished leaves identification method, and was supposed to be best artificial inoculation and identification method in vitro. [Conclusion] This research had provided a scientific method for safe and effective researches on chrysanthemum white rust, in order to control the occurrence and diffusion of this quarantine disease.展开更多
Language testing is an important link in language teaching,in this paper,the two important criteria of language test the reliability and validity has carried on the detailed elaboration,in order to a language teacher ...Language testing is an important link in language teaching,in this paper,the two important criteria of language test the reliability and validity has carried on the detailed elaboration,in order to a language teacher proposition and evaluation test more scientific.展开更多
作者以他个人的观点,对该文献中重要部分进行了点评,指出:空间软件地面可靠性测试尽管困难重重且有诸多限制,但不能放松甚至放弃执行现有的软件地面测试标准;应从"精神号"火星探测器飞行失败中吸取教训,加强软件地面测试,包...作者以他个人的观点,对该文献中重要部分进行了点评,指出:空间软件地面可靠性测试尽管困难重重且有诸多限制,但不能放松甚至放弃执行现有的软件地面测试标准;应从"精神号"火星探测器飞行失败中吸取教训,加强软件地面测试,包括传统软件黑盒和白盒测试方法中的典型测试项目(如:健壮测试、应力测试、极值测试、随机测试等);已经公布的新软件研发标准——Aerospace Report No.TOR-2004(3909)-3537,Software Development Standard for Space Systems值得我们参考。展开更多
Assays that measure steroid hormones in patient care, public health, and research need to be both accurate and precise, as these criteria help to ensure comparability across all clinical and research applications. Thi...Assays that measure steroid hormones in patient care, public health, and research need to be both accurate and precise, as these criteria help to ensure comparability across all clinical and research applications. This review addresses major issues relevant to assay variability and describes recent activities by the US Centers for Disease Control and Prevention （CDC） to improve assay performance. Currently, high degrees of accuracy and precision are not always met for testosterone and estradiol measurements; although technologies for steroid hormone measurement have advanced significantly, measurement variability within and across laboratories has not improved accordingly. Differences in calibration and specificity are discussed as sources of variability in measurement accuracy. Ultimately, a combination of factors appears to cause inaccuracy of steroid hormone measurements, with nonuniform assay calibration and lack of specificity being two major contributors to assay variability. Within-assay variability for current assays is generally high, especially at low analyte concentrations. The CDC Hormone Standardization （HoSt） Program is improving clinical assays, as evidenced by a 50% decline in mean absolute bias between mass spectrometry assays and the CDC reference method from 2007 to 2011. This program provides the measurement traceability to CDC reference methods and helps to minimize factors affecting measurement variability.展开更多
This paper is a review of the past research of mechanical testing methods for natural fibre honeycomb sandwich structure as well as failure modes analysis at a microscopic level by using Scanning Electron Microscope (...This paper is a review of the past research of mechanical testing methods for natural fibre honeycomb sandwich structure as well as failure modes analysis at a microscopic level by using Scanning Electron Microscope (SEM). As the world is garnering attention towards renewable resources for environmental purposes, studies of natural fibre have been increasing as well as the application of natural fibre throughout various industries such as aerospace, automobiles, and construction sectors. This paper is started with brief information regarding the honeycomb sandwich structure, introduction to natural fibre, its applications as well as the factors affecting the performances of the structure. Next, the mechanical testing methods are listed out as well as the expected outcomes obtained from the respective testing. The mechanical properties are also identified by conducting lab tests according to the ASTM standard for sandwich and core structures. The microstructure of the deformed samples is then examined under Scanning Electron Microscope (SEM) by using different magnifications to study the failure mechanisms of the samples. The images obtained from the SEM test are analyzed by using fractography which will show the failure modes of the samples. This article is based on past research conducted by professional on the related topic.展开更多
In this paper, we analyze the features and distinctions of 6 classical algorithms： greedy algorithm （G）, greedy evolution algorithm （GE）, heuristics algorithm （H）, greedy heuristic G （GRE）, integer linear pro...In this paper, we analyze the features and distinctions of 6 classical algorithms： greedy algorithm （G）, greedy evolution algorithm （GE）, heuristics algorithm （H）, greedy heuristic G （GRE）, integer linear programming algorithm （ILP） and genetic algorithm （GA） to ensure the main influencing factors-the performance of algorithms and the running time of algorithms. What＇s more, we would not only present a research design that aims at gaining deeper understanding about the algorithm classification and its function as well as their distinction, but also make an empirical study in order to obtain a practical range standard that can guide the selection of reduction algorithms. When the size of a test object （product of test requirements and test cases） is smaller than 2000×2000, G algorithm is the commonly recommended algorithm. With the growth of test size, the usage of GE and GRE becomes more general.展开更多
基金supported in part by Explosion Prevention Technology and Rotating Machines(EPT&RM)laboratory,South African Bureau of Standards(SABS),Pretoria,South Africa.
文摘The induction motor,which converts electrical energy into mechanical energy,has been recognized as the cornerstone of industrialization.The rotor of an induction motor can be either a squirrel cage rotor or a wound-type rotor,both existing as magnetless topologies.Three-phase squirrel cage induction motors are frequently utilized in industrial drives because they are dependable,have high starting torque,are selfstarting and affordable.Single-phase induction motors,on the other hand,are commonly used for small loads such as domestic appliances in form of modest fans,pumps and electric power tools.In South Africa,there have been reports of fires and explosions resulting in live and property loss because of induction motors that have not been thoroughly tested or are incorrectly labelled in terms of ratings,electrical safety and performance.The goal of this study is targeted at preventing end-user injuries and failures caused by non-compliant induction motors,by evaluating locally manufactured/imported induction motors based on tests and evaluation from standards(IEC and SANS).The study is conducted using experimental procedures at the Explosion Prevention Technology and Rotating Machines(EPT and RM)laboratory,South African Bureau of Standards(SABS),South Africa.The main finding from the study shows differences in the nameplate characteristics of various induction motors which could have detrimental effects such as production and operational downtime in their end-use industries,at later stages.
文摘The symposium on inspection and testing bodies in the special action on standards comparison and complianee of 10,000 enterprises of 1,000 sectors in 100 cities was held in Beijing on April 16,which was attended by more than 70 representatives from SAMR and inspection and testing bodies.
文摘China is the biggest country of rice production and consumption in the world;more than 50% of the population feeds chiefly on rice. The quality of rice and its role as a staplefood carry much weight. The rice qualities are those aspects concerning processing, appearance,cooking, nutrition and safety of the product. The study, formulation and implementation of standardson rice qualities and testing bear heavily on the improving of rice qualities, human health,substitution of rice varieties, promoting quality rice production and regulating rice market.
文摘Based on the analysis of food testing standards (according to parameters, categories and methods), this paper puts forward an integrated reference method for food testing standards. At the same time, the innovation of food testing methods puts forward some "normal" requirements from aspects of coverage, recovery rate and consistency with determination standards.
基金Tianshui City Science and Technology Support Plan Project:2023-FZJHK-2813。
文摘As science and technology continue to develop,power equipment has become an indispensable part of industrial production and daily life.Whether it is the precise automation machinery utilized on production lines or the convenient electrical appliances found in households,their functionality relies heavily on electrical technology.Nonetheless,without stringent safety and performance assurances,these devices could potentially endanger lives and property.Thus,this paper explores the development strategy for establishing a standardized system within the electrical testing service industry,aiming to ensure safety and reliability.
基金Grant from National Institute of Infectious Diseases(NIID)National Department Public Benefit Research Foundation (201103032)
文摘The World Health Organization （WHO） standard assay for determining antibody level is the rapid fluorescent focus inhibition test （RFFIT） and is used to determine the degree of immunity after vaccination against rabies. To compare the difference in RFFIT results between the laboratories of The National Institute of Infectious Disease in Japan （NIID） and the Chinese Centre for Disease Control （CCDC） as well the influence of the choice of standard serum （STD） for the detection, the two laboratories detection methods were simultaneously manipulated by RFFIT. The reference serums used in NIID and the WHO standard serum used in CCDC were compared in the same RFFIT detection to determine the titer of four sera samples C1, Sl, S2 and S4 in parallel, and the titers of the detected sera samples were calculated using the standard formula for neutralizing antibody titer. No significant difference was found in RFFIT methods from the two laboratories and the RFFIT testing procedures of the two laboratories have good consistency. However, different titers were obtained with the tentative internal standard serum （TI-STD） produced by adjusting to 2.0 IU of WHO standard serum in NIID and the WHO STD. The titer determined with the TI-STD was higher than that determined with WHO STD, This difference appears to be significant and requires further investigation
文摘This article introduces the composition and working principle of home appliance control board automation testing equipment,elaborates on the importance of key technical indicators,explains the integrated design of functional modules,signal processing modules,and data analysis modules,and covers aspects such as the application of machine learning algorithms and the establishment of fault waveform databases.Finally,it looks forward to the development of intelligent testing systems and emphasizes the importance of building a standardized testing system.
基金Hubei Provincial Medical Institutions at all levels of basic drugs and drug bridging support policy projectsResearch on the Integrated Development of Disease Prevention and Control and Medical Services in the XPCC under the Background of Healthy China (Grant No. BTJKJ2024003)。
文摘The purpose of this study is to evaluate the price and composition of blood glucose meters and blood glucose test papers in Hubei Province,so as to improve the affordability of blood glucose monitoring for diabetes patients.Using the standard survey method jointly developed by the World Health Organization(WHO)and Health Action International(HAI)for drug price composition analysis,central level data was collected through literature review,policy review,and interviews with key informants.Field research was conducted in Wuhan and Yichang to trace price data at various levels of the supply chain.At the central level,data shows that China has implemented multiple policies related to the management and pricing of blood glucose meters and test strips,but has not yet introduced price restrictions for blood glucose meters and test strips;At the supply chain level,data shows that the price composition of blood glucose meters and test strips in Hubei Province is mainly composed of manufacturer prices and retail markups,followed by supply chain taxes and wholesale markups.It can be seen from this that China has established a comprehensive medical device registration,sales,quality control and management standard system through a series of policies.At present,China has not issued price policies for blood glucose meters and blood glucose test papers.Therefore,we can reduce product prices by including medical insurance,government subsidies,competitive bidding,and reducing supply chain taxes,thus improving the affordability of blood glucose monitoring for diabetes patients.
文摘There are a few standards reported in the literature for testing and evaluation of thermal performance of solar concentrators based on sensible heating of working fluid. The preceding standard measures only the cooking efficiency and cooking capacity. Apart from thermal efficiency, there is an imperative need for other important parameters of the solar concentrators such as its stagnation temperature, cooking capacity, cost per watts delivered, weight of the cooker, ease of handling and aesthetics. The characterization of a concentrator at its operating temperature settles appropriate size and type of concentrator for any thermal application. The performance test is conducted at Chandwad (20.3292°N, 74.2444°E), Maharashtra and the proposed protocol aims for evaluation of thermal performance of solar cooking system and standardization of reporting the test results so that anyone can easily recognize and use it.
文摘The objective of this work was to study the use of standard equipment in amplitude and frequency tests of dental scaler tip according to ISO 18397.Four types of standard equipment:a laser displacement sensor,a microscope,a tachometer,and an ultrasonic frequency meter,were experimentally investigated to test a tip.The standard laser displacement sensor and the standard microscope were used to test the unloaded amplitude of the scaler tip.It was found that two types of standard equipment were able to measure the unloaded amplitude of the tip.The standard microscope was also employed for the loaded amplitude test.This test was performed by pressing the scaler tip with a load of 1 N,which was measured by a load cell set.The peak-to-peak amplitude found from the test was 116.7 m.The frequency test of the scaler tip was conducted using the standard laser displacement sensor,the tachometer and the ultrasonic frequency meter.All three types of standard equipment were found to be able to test the frequency of the tip without cooling liquid.Nevertheless,only the standard tachometer was capable of measuring the frequency of the tip with cooling liquid applied.
文摘A comprehensive overview of standardized testing system for ESL （English as a Second Language） students in U.S kindergarten thru grade 12 public school system is reviewed within the context of basis on federal and state laws, as well as instructional basis. Identification process of LEP （Limited English Proficient） students via nomination, testing and testing criteria to be identified as LEP, hence ESL if placed in the program is defined in detail Standardized testing process of these students based on the federal AYP （Adequate Yearly Progress） measures through regular state standardized tests depending on three types of instructional program that LEP student is placed in the school that are Bilingual Education Program, ESL Program, and Two-Way Immersion Dual Language Programs are described. Standardized testing process of these students based on the federal AYP measures through other means if exempted from regular state standardized tests such as LAT （Linguistically Accommodated Testing） and the conditions to be exempted are discussed in detail. Holistically rated English Language Proficiency Assessments that are implemented to fulfill federal AMAOs （Annual Measurable Achievement Objectives） measures are defined briefly. Physical features of LAT test as well as direct and indirect accommodations for LAT reading, mathematics and science tests are defined via the accommodation needed and the type of assistance provided. Lastly, testing criteria to exit LEP status and other issues concerning exiting LEP status are reviewed
文摘This paper introduces the common technical problems in the assembly process of gate valve, globe valve and swing check valve, analyzes the causes, and according to different reasons, gives the solutions and measures for the field assembly of valves. This paper introduces the pressure test inspection requirements of gate valves, globe valves and swing check valves and the determination of leakage methods. Introduce the common domestic and foreign standards for valve pressure test and leakage inspection.
基金Supported by the"Eleventh Five-Year"National Technology Support Program"Breeding of New Varieties of High Yield and Quality of Major Commercial Flowers"(2006BAD01A18)the Postdoctoral Research Fund of Shenyang Agricultural University~~
文摘[Objective] This research aimed at exploring an effective way for inoculation and identification of chrysanthemum white rust under controlled conditions. [Method] By combining the observation methods with the naked eye and under optical microscope, we had established the identification standards for chrysanthemum white rust with six classifications and optimized artificial inoculation methods in vitro. [Result] The results showed that bottled cuttings identification method and petri dished leaves identification method both can be used for identification in vitro of chrysanthemum white rust, bottled cuttings identification method had shown better effects than petri dished leaves identification method, and was supposed to be best artificial inoculation and identification method in vitro. [Conclusion] This research had provided a scientific method for safe and effective researches on chrysanthemum white rust, in order to control the occurrence and diffusion of this quarantine disease.
文摘Language testing is an important link in language teaching,in this paper,the two important criteria of language test the reliability and validity has carried on the detailed elaboration,in order to a language teacher proposition and evaluation test more scientific.
文摘作者以他个人的观点,对该文献中重要部分进行了点评,指出:空间软件地面可靠性测试尽管困难重重且有诸多限制,但不能放松甚至放弃执行现有的软件地面测试标准;应从"精神号"火星探测器飞行失败中吸取教训,加强软件地面测试,包括传统软件黑盒和白盒测试方法中的典型测试项目(如:健壮测试、应力测试、极值测试、随机测试等);已经公布的新软件研发标准——Aerospace Report No.TOR-2004(3909)-3537,Software Development Standard for Space Systems值得我们参考。
文摘Assays that measure steroid hormones in patient care, public health, and research need to be both accurate and precise, as these criteria help to ensure comparability across all clinical and research applications. This review addresses major issues relevant to assay variability and describes recent activities by the US Centers for Disease Control and Prevention （CDC） to improve assay performance. Currently, high degrees of accuracy and precision are not always met for testosterone and estradiol measurements; although technologies for steroid hormone measurement have advanced significantly, measurement variability within and across laboratories has not improved accordingly. Differences in calibration and specificity are discussed as sources of variability in measurement accuracy. Ultimately, a combination of factors appears to cause inaccuracy of steroid hormone measurements, with nonuniform assay calibration and lack of specificity being two major contributors to assay variability. Within-assay variability for current assays is generally high, especially at low analyte concentrations. The CDC Hormone Standardization （HoSt） Program is improving clinical assays, as evidenced by a 50% decline in mean absolute bias between mass spectrometry assays and the CDC reference method from 2007 to 2011. This program provides the measurement traceability to CDC reference methods and helps to minimize factors affecting measurement variability.
文摘This paper is a review of the past research of mechanical testing methods for natural fibre honeycomb sandwich structure as well as failure modes analysis at a microscopic level by using Scanning Electron Microscope (SEM). As the world is garnering attention towards renewable resources for environmental purposes, studies of natural fibre have been increasing as well as the application of natural fibre throughout various industries such as aerospace, automobiles, and construction sectors. This paper is started with brief information regarding the honeycomb sandwich structure, introduction to natural fibre, its applications as well as the factors affecting the performances of the structure. Next, the mechanical testing methods are listed out as well as the expected outcomes obtained from the respective testing. The mechanical properties are also identified by conducting lab tests according to the ASTM standard for sandwich and core structures. The microstructure of the deformed samples is then examined under Scanning Electron Microscope (SEM) by using different magnifications to study the failure mechanisms of the samples. The images obtained from the SEM test are analyzed by using fractography which will show the failure modes of the samples. This article is based on past research conducted by professional on the related topic.
基金Supported by the National Natural Science Foundation of China(10904080)
文摘In this paper, we analyze the features and distinctions of 6 classical algorithms： greedy algorithm （G）, greedy evolution algorithm （GE）, heuristics algorithm （H）, greedy heuristic G （GRE）, integer linear programming algorithm （ILP） and genetic algorithm （GA） to ensure the main influencing factors-the performance of algorithms and the running time of algorithms. What＇s more, we would not only present a research design that aims at gaining deeper understanding about the algorithm classification and its function as well as their distinction, but also make an empirical study in order to obtain a practical range standard that can guide the selection of reduction algorithms. When the size of a test object （product of test requirements and test cases） is smaller than 2000×2000, G algorithm is the commonly recommended algorithm. With the growth of test size, the usage of GE and GRE becomes more general.
