A generic framework for qualifications of digital twins in maintenance

Digital twins have emerged as a promising technology for maintenance applications,enabling organizations to simulate and monitor physical assets to improve their performance.In Operation and Maintenance(O&M),digital twin facilitates the diagnosis and prognosis of critical assets,forming the basis for smart maintenance planning and reducing downtime.However,there is a lack of standardized approaches for the qualifications of digital twins in maintenance,leading to low trustworthiness and limiting its application.This paper proposes a novel framework for the qualifications of digital twins in maintenance based on five pillars,namely fidelity,smartness,timeliness,integration,and standard compliance.We demonstrate the effectiveness of the framework through two case studies,showing how it can be implemented on digital twins for preventive maintenance and condition-based maintenance.Our proposed framework can help organizations across different industrial domains develop and implement digital twins in maintenance more effectively and efficiently,leading to significant benefits in terms of cost reduction,performance improvement,and sustainability.

Marital Stress and Married Working Women in Nigeria:the Role of Coping Strategies,Self-Concept and Educational Qualification

In this 21st century a lot of women are experiencing marital challenges due to the various and important roles they perform in the home and in the society,which may require some psychological remedies.The research was on marital stress and married working women:the role of coping strategies,self-concept and educational qualification.Three hundred and seventy-seven(377)participants whose ages were between 25 to 55 years(mean 40.63 and SD 7.59)participated in the study.Three research instruments were used for data collection while three-way Analysis of Variance was used for data analysis.Result disclosed that emotion-focused strategies yielded less manifestation of marital stress(1,369)=4.44,sig.=.036;in the same manner,those with higher educational qualification presented less manifestation of marital stress(1,369)=6.33,sig.=.012.It was equally specified that coping strategies together with self-concept had a joint impact on marital stress(1,369)=5.88,sig.=.016;a joint influence was also observed between self-concept and educational qualification on marital stress(1,369)=4.18,sig.=.042.Hence,married working women should strive for higher education and also use emotion-focused coping strategies in dealing with marital stress.

THE TANGENT CONES ON CONSTRAINT QUALIFICATIONS IN OPTIMIZATION PROBLEMS

This article proposes a few tangent cones,which are relative to the constraint qualifications of optimization problems.With the upper and lower directional derivatives of an objective function,the characteristics of cones on the constraint qualifications are presented.The interrelations among the constraint qualifications,a few cones involved, and level sets of upper and lower directional derivatives are derived.

Knowledge expression and reasoning process in an expert system for welding procedure qualification

After analyzing the welding procedure knowledge in Chinese national standards for welding procedure qualification of steel pressure vessel from the point of establishing expert system, it can be divided into five types of knowledge, i. e. practice, definition, regularity, process and description knowledge. The knowledge expression methods are established according to the different type of welding procedure knowledge. The reasoning process based on rule is adopted. And the reasoning engine is embedded among objects integrated with the knowledge base.

Qualification of Atomic Absorption Spectrometer in Prospective View of Pharmaceutical Analysis

AAS was qualified as per pharmacopoeia requirements. Copper, manganese, mercury and cadmium hallow cathode lamps were used for qualification purposes. Design qualification and installation qualification met the criteria of user requirements. Wavelength accuracy and reproducibility, resolution and baseline stability are in compliance with user requirements. Characteristics concentration or sensitivity, detection limit and characteristics mass were performed as a part of operational qualification which is 0.062 μg/mL, 0.00354 μg/mL, 1.41 pg respectively. Results of % RSD for precision study is 0.352 and 0.487 for flame and graphite furnace mode respectively fulfilled criteria of qualification. Performance qualification results of 20 consecutive days demonstrate the predetermined specification. Analytical instrument qualification and method validation relationship is also described by assay performed on haemodialysis concentrate. Good precision (2) greater than 0.9997 for potassium, magnesium and calcium linear curves, lower detection limits for all three ingredients and robust assay data as a part of validation studies conform the qualified AAS for its intended application.

Qualification Test for the Reliability of Diver Gas Recovery System

A qualification test for the reliability of a newly-developed Diver Gas Recovery System (DGRS) was carried out in the Naval Medical Research Institute of the People's Liberation Army, China from March 29 to April 2, 1995. A sequential test plan of high discrimination ratio for the mean time between failures (MTBF) was adopted. The test procedures simulated those of a 300 msw dive. A hyperbaric breathing machine was used for the simulation of diver's respiratory functions. Parameters, such as diving depth, respiratory minute volume (RMV), CO2 production, gas flow rate, partial pressure of carbon dioxide, and ambient temperature and himidity were all displayed and recorded with a microcomputer system. The results indicated that no failure occurred during the 91.5 h operation. According to the acceptance and rejection criteria specified in the statistical test plan, a no-failure score in the 88 h operation is acceptable. Therefore, the DGRS has been demonstrated to meet the requirements of MTBF specified in the contract.

Cooperation between China and Germany for twenty years as well as development of international welding training and qualification in China

Chinese Welding Training and Qualification Committee (CANB) was awarded the authorisation of IIW in 2000, and has issued nearly 2000 IIW diplomas by the end of 2004. Since Harbin Welding Training Institute(WTI Harbin) was founded based on Sino-German cooperation in 1984, it has trained all kinds of welding personnel 20000 and it made important contribution to the up-to-date system introduction of international welding training to China. The common questions in Germany foreign aid programs are: when German experts were on site, the project was on the operation; when he/they left, only memory was left. The outstanding achievements of Harbin Welding Training Institute tell us: when German experts were away, the cooperation program is not only run normally, but also gets persistent development, it is the successful model among the cooperation projects between China and Germany.

Efficient Method for Accelerated Reliability Qualification Testing

Based on the theoretical inference and experiment verification,a method was proposed to carry out the accelerated reliability qualification testing. First,theoretical inference was used to get the acceleration coefficients of super Gauss vibration stress and temperature stress. Then, by applying these coefficients, an accelerated reliability qualification testing curve was obtained from the standard tests. Finally,the actual experiment on a digital marine control device was carried out under the proposed testing method.The experiment result shows that the proposed method can reduce the total experiment time and improve the efficiency of the reliability qualification test.

A Note on the Guignard Constraint Qualification and the Guignard Regularity Condition in Vector Optimization

Some remarks are made on the use of the Abadie constraint qualification, the Guignard constraint qualifications and the Guignard regularity condition in obtaining weak and strong Kuhn-Tucker type optimality conditions in differentiable vector optimization problems.

Risk Based Technology Qualification Method for HPHT Well

With the increasing demand for new technologies in HPHT (high pressure high temperature) wells, more and more attention has been paid to the system of technical qualifications. Most established norms, standards and recommended practices are written in prescribed formats, setting out methods, procedures and acceptance criteria for product design, manufacture and testing. However, established norms, standards or recommended practices may not adequately cover new technologies or applications. The technical qualification system is established in this paper, which can identify the potential failure modes and some activities in order to control the uncertainties and increase confidence of using new technology. A risk-based technical qualification system is used to assess non-traditional operations. It includes following seven main steps: system breakdown, technology assessment and classification, technical novelty, failure model and risk analysis, risk-based qualification planning and participation level development. The core of technical qualification system is to understand the ways and causes of system failure, and to carry out corresponding activities to provide evidence that the system will not fail. Through the technical identification process, the detailed equipment/operation specifications and identification requirements have been formulated. Different levels of participation are assigned for each eligibility activity, depending on the hazard and risk. It is proved that the application of the technical qualification principle in the systematic evaluation and control of the risks of new technologies or new applications is successful. In HPHT wells in particular, operators can move from a reactive approach to a proactive approach.

Structural Design Optimization of a Vertical Axis Wind Turbine for Seismic Qualification and Lightweight

Recently, there is a growing interest in seismic qualification of ridges, buildings and mechanical equipment worldwide due to increase of accidents caused by earthquake. Severe earthquake can bring serious problems in the wind turbines and eventually lead to an interruption to their electric power supply. To overcome and prevent these undesirable problems, structural design optimization of a small vertical axis wind turbine has performed, in this study, for seismic qualification and lightweight by using a Genetic Algorithm (GA) subject to some design constraints such as the maximum stress limit, maximum deformation limit, and seismic acceleration gain limit. Also, the structural design optimizations were conducted for the four different initial design variable sets to confirm robustness of the optimization algorithm used. As a result, all the optimization results for the 4 different initial designs showed good agreement with each other properly. Thus the structural design optimization of a small vertical-axis wind turbine could be successfully accomplished.

Regulations on the Management of the Qualification to Engage in the Business Operations concerning Shares Owned by Foreign Investors

With a view to standardizing the business operationsrelating to foreign investment of domestic and overseas secu-rities organizations and protecting the legitimate rights andinterests of investors,the China Security Regulatory Commis-sion has promulgated the Provisional Regulations on theManagement of the Qualification of Domestic and OverseasSecurities Organizations to Engage in the Business Opera-tions concerning Shares Owned by Foreign Investors.TheseRegulations enter into force on December 1.1996.The wholetext is as follows:Chapter 1 General PrinciplesArticle 1 With a view to standardizing the businessoperations of domestic and overseas securities organizationswhich relate to shares owned by foreign investors and pro-

Guignard’s Constraint Qualification (GCQ) and Multiobjective Optimisation Problems

Investigation of optimality conditions has been one of the most interesting topics in the theory of multiobjective optimisation problems (MOP). To derive necessary optimality conditions of MOP, we consider assumptions called constraints qualifications. It is recognised that Guignard Constraint Qualification (GCQ) is the most efficient and general assumption for scalar objective optimisation problems;however, GCQ does not ensure Karush-Kuhn Tucker (KKT) necessary conditions for multiobjective optimisation problems. In this paper, we investigate the reasons behind that GCQ are not allowed to derive KKT conditions in multiobjective optimisation problems. Furthermore, we propose additional assumptions that allow one to use GCQ to derive necessary conditions for multiobjective optimisation problems. Finally, we also include sufficient conditions for multiobjective optimisation problems.

On Basic Constraint Qualifications for Infinite System of Convex Inequalities in Banach Spaces

The BCQ and the Abadie CQ for infinite systems of convex inequalities in Banach spaces are characterized in terms of the upper semi-continuity of the convex cones generated by the subdifferentials of active convex functions. Some relationships with other constraint qualifications such as the CPLV and the Slate condition are also studied. Applications in best approximation theory are provided.

Optimal procurement strategy of fresh produce retailer under stochastic product qualification and market demand

Consider an optimal procurement strategy for fresh produce,which is a type of perishable product.Due to the different quality provided by each manufacturer,the fresh produce qualification rates are dissimilar.Simultaneously,consumers demand is influenced by the freshness and price of products,as a result,the demand in the market is not fixed.In this scenario,how a particular retailer should develop an optimal procurement strategy will be a core issue in supply chain management.In order to address the above questions,the Bayesian approach is adopted to explore retailer optimal procurement strategies with uncertainty about product supply and market demand.Finally,simulation data are used to analyse the results of the proposed model and expected non-random model to illustrate the validity and feasibility of the proposed model.

Higher Vocational and Professional Higher Education Qualifications in the European Level 5 Area——A basis for more international cooperation

The'European Level 5 Area'(EL5A)is a relatively new concept for Europe,giving an excellent opportunity to link the sectors for Vocational Education and Training(VET)and Higher Education(HE)to each other.Then it is about looking at qualifications at level 5 of the European Qualifications Framework(EQF)for Lifelong Learning and using them

A CONSTRAINT QUALIFICATION FOR CONVEX PROGRAMMING

This paper derives a new constraint qualification for nondifferential convex programming problem, by using the distance between the feasible set and the perturbed feasible sets. If the feasible sot is bounded, then this constraint qualification is weaker than Stater's constrains qualification.

Women Prove Theil Mayoral Qualifications

OF the 517 large and small cities in the country, more than 300 have women mayors and vice mayors. These women play an important role in the construction and development of their cities. Ordinary Chinese people like to call their local officials "father-and- mother officials," but these

采用反吹、微流控技术分析原油中的轻烃组分

利用程序升温蒸发进样器、反吹技术和微流控装置分析原油中的C5-C13轻烃组分，用一根HPPONA色谱柱分离，同时得到保留时间相同的火焰离子化检测信号和质谱检测信号，为原油中轻烃组分的色谱定性提供了新的有力工具。该方法中所用的色谱柱使用寿命长，分离效果好，对平湖4井油样中C5～C13馏分的分离得到了可用质谱定性的峰约290个（尚有不少混合峰存在），较难分离的物质对t-1，2-二甲基环戊烷与2-乙基戊烷得到了较好的分离，2-乙基戊烷峰得到非常好的质谱图，是目前研究原油中轻烃组分分析的有效手段。同时应用微流控装置后可在质谱仪不停机的条件下更换色谱柱。

英、澳、美中高职衔接课程体系的构建及对我国的借鉴

英国通过资格与学分框架(QCF)实现了中高职课程体系衔接,澳大利亚通过TAFE课程的开发实现中高职课程体系的衔接,美国通过职业生涯与技术教育课程实现中高职课程体系衔接。他们在中高职衔接的课程开发制度、科学的课程开发依据和系统的课程开发流程、注重职业教育课程的职业导向性以及强调文化课与专业课衔接、教育和劳动力市场需求衔接的诸多做法值得我国借鉴。