High Quality Requirements Research Articles

Automatic Repair of Semantic Defects Using Restraint Mechanisms

Recently, software, especially CPS and Internet of Things (IoT), increasingly have high requirements for quality, while program defects exist inevitably duo to the high complexity. Program defect repair faces serious challenges in that such repairs require considerable manpower, and the existing automatic repair approaches have difficulty generating correct patches efficiently. This paper proposes an automatic method for repairing semantic defects in Java programs based on restricted sets which refer to the interval domains of related variables that can trigger program semantic defects. Our work introduces a repair mechanism symmetrically combining defect patterns and repair templates. First, the program semantic defects are summarized into defect patterns according to their grammar and semantic features. A repair template for each type of defect pattern is predefined based on a restricted-set. Then, for each specific defect, a patch statement is automatically synthesized according to the repair template, and the detected defect information is reported by the static detection tool (DTSJava). Next, the patch location is determined by the def-use chain of defect-related variables. Finally, we evaluate the patches generated by our method using DTSJava. We implemented the method in the defect automatic repair prototype tool DTSFix to verify the effect of repairing the semantic defects detected by DTSJava in 6 Java open-source projects. The experimental results showed that 109 of 129 program semantic defects were repaired.

Hot Isostatic Pressing of Aluminum–Silicon Alloys Fabricated by Laser Powder-Bed Fusion

Hot isostatic pressing can be utilized to reduce the anisotropic mechanical properties of Al–Si–Mg alloys fabricated by laser powder-bed fusion (L-PBF). The implementation of post processing densification processes can open up new fields of application by meeting high quality requirements defined by aircraft and automotive industries. A gas pressure of 75 MPa during hot isostatic pressing lowers the critical cooling rate required to achieve a supersaturated solid solution. Direct aging uses this pressure related effect during heat treatment in modern hot isostatic presses, which offer advanced cooling capabilities, thereby avoiding the necessity of a separate solution annealing step for Al–Si–Mg cast alloys. Hot isostatic pressing, followed by rapid quenching, was applied to both sand cast as well as laser powder-bed fused Al–Si–Mg aluminum alloys. It was shown that the critical cooling rate required to achieve a supersaturated solid solution is significantly higher for additively manufactured, age-hardenable aluminum alloys than it is for comparable sand cast material. The application of hot isostatic pressing can be combined with heat treatment, consisting of solution annealing, quenching and direct aging, in order to achieve both a dense material with a small number of preferred locations for the initiation of fatigue cracks and a high material strength.

Employment Prospects of Graduates From Sino-Foreign Cooperative Universities in China

This article aims to examine the employment prospects of graduates from Sino-foreign cooperative universities (SFCUs) compared with those from local Chinese universities. Drawing on the annual employment quality reports released by six SFCUs, the findings indicated that SFCU graduates had distinct advantages in terms of both further study and direct employment. Specifically, the overall employment rate reached 95.84%; over half of the graduates pursued further study abroad in world-class foreign universities, close to one-third continued further studies in elite domestic universities, and one-sixth were employed by transnational or local large organizations. These results suggest that SFCU graduates were equipped with distinct competitive advantages for employment, further supported by an affluent family background and the high-quality requirement for admission. Meanwhile, the findings also raise concerns about brain drain, economic flows, overeducation, reduced entrepreneurial passion, and unemployment dilemma for graduates from lesser known SFCUs.

Measuring the bore straightness during reaming with sensoric tools

Reaming plays a crucial role in production to meet the high quality requirements of precision bore machining. It is either directly responsible for the final component quality or influences subsequent processes such as honing. The narrow tolerances are usually monitored by measuring random samples in mass production due to cost efficiency. Having a closer look at an exemplary process chain for the production of hydraulic valves shows the possibility to adapt the honing parameters which reduces processing time and costs. However, the bore straightness after the reaming process has to be known. In this paper an approach is presented which allows to record the bore straightness within the productive time. For this purpose, a sensory reaming system is developed. It can be used without additional components in the machine tool and thus integrated into existing machining processes. Cutting tests show that the system is able to measure the bore straightness as good as sensing probes used in machine tools.

Technical project management for meeting high quality requirements of machined parts

A project is a sequence of unique, complex and related tasks that have a common goal, and which are intended to be completed within a specified period of time without exceeding the set budget, in accordance with the previously assumed requirements. In the case of typical technical projects two situations are possible. If the parameters of the manufactured element turn out to be correct (they meet the technological requirements), then the angle of the main surface is corrected, i.e. the change in the plane’s geometry, which is supposed to improve the parameter of the element. If its parameters are not correct, it means that an error occurred during machining and its surface should be improved. This sequence is conducted to fulfill the quality requirements. In the paper is presented the results of investigation the process of improving the technological process.

Site-specific machine learning predictive fertilization models for potato crops in Eastern Canada.

Statistical modeling is commonly used to relate the performance of potato (Solanum tuberosum L.) to fertilizer requirements. Prescribing optimal nutrient doses is challenging because of the involvement of many variables including weather, soils, land management, genotypes, and severity of pests and diseases. Where sufficient data are available, machine learning algorithms can be used to predict crop performance. The objective of this study was to determine an optimal model predicting nitrogen, phosphorus and potassium requirements for high tuber yield and quality (size and specific gravity) as impacted by weather, soils and land management variables. We exploited a data set of 273 field experiments conducted from 1979 to 2017 in Quebec (Canada). We developed, evaluated and compared predictions from a hierarchical Mitscherlich model, k-nearest neighbors, random forest, neural networks and Gaussian processes. Machine learning models returned R2 values of 0.49-0.59 for tuber marketable yield prediction, which were higher than the Mitscherlich model R2 (0.37). The models were more likely to predict medium-size tubers (R2 = 0.60-0.69) and tuber specific gravity (R2 = 0.58-0.67) than large-size tubers (R2 = 0.55-0.64) and marketable yield. Response surfaces from the Mitscherlich model, neural networks and Gaussian processes returned smooth responses that agreed more with actual evidence than discontinuous curves derived from k-nearest neighbors and random forest models. When conditioned to obtain optimal dosages from dose-response surfaces given constant weather, soil and land management conditions, some disagreements occurred between models. Due to their built-in ability to develop recommendations within a probabilistic risk-assessment framework, Gaussian processes stood out as the most promising algorithm to support decisions that minimize economic or agronomic risks.

ANALYSIS OF THE MACHINING SCHEME OF COMPLEX-PROFILES SHELLS OF ROTATION

Modern engineering products have complex geometry with high quality requirements, are made from new materials that is provoked the development and use the mechanisms of parallel structure, which are distinguished by high rigidity characteristics, as well as have wide functional capabilities. The precision problems of machining of complex-profile low-rigid parts, in particular thin-walled pyroceram shell are considered in article. Scheme of machining affect the accuracy and depends on the capabilities of technological equipment. Rationale for scheme of machining a thin-walled casing is presented in article. The accuracy of machining the outer profile of the casing was simulated for last step of diamond grinding. The simulation was performed for a traditional scheme of machining, which is performed for a lathe with an aggregate grinding head and a direct copying system, and for a scheme of machining for equipment that is fitted out with a mechanism with a parallel structure. The model of formation of the machining error is based on using the equations of relative displacement of the technological bases of the workpiece and the contact point of the working surface of the diamond wheel with the workpiece. The model takes into account the static and dynamic characteristics of the technological system and force factors during grinding. The calculations have confirmed that proposed solutions are able to provide the necessary machining precision. Changing the machining scheme of the workpiece and performing such machining on equipment with mechanisms of parallel structures eliminates the basing error, increases the rigidity of the technological system, and provides the possibility of turning the axis of the diamond wheel with the required angle.

The Application of Computer 3D Design in Green Building

In the current era, the conventional architectural design process has been difficult to adapt to the high performance and high quality requirements of green building standards. By analyzing the necessity of applying 3d design in green building design, this paper studies the feasibility of applying 3d design in green building design from the aspects of the characteristics of green building and the advantages of 3d design. The application of computer 3d technology in green building design can better highlight the economy, rationality and maneuverability of computer 3d in building design.

BSS: A Burst Error-Correction Scheme of Multipath Transmission for Mobile Fog Computing

In the scenario of mobile fog computing (MFC), communication between vehicles and fog layer, which is called vehicle-to-fog (V2F) communication, needs to use bandwidth resources as much as possible with low delay and high tolerance for errors. In order to adapt to these harsh scenarios, there are important technical challenges concerning the combination of network coding (NC) and multipath transmission to construct high-quality V2F communication for cloud-aware MFC. Most NC schemes exhibit poor reliability in burst errors that often occur in high-speed movement scenarios. These can be improved by using interleaving technology. However, most traditional interleaving schemes for multipath transmission are designed based on round robin (RR) or weighted round robin (WRR), in practice, which can waste a lot of bandwidth resources. In order to solve those problems, this paper proposes a novel multipath transmission scheme for cloud-aware MFC, which is called Bidirectional Selection Scheduling (BSS) scheme. Under the premise of realizing interleaving, since BSS can be used in conjunction with a lot of path scheduling algorithms based on Earliest Delivery Path First (EDPF), it can make better use of bandwidth resources. As a result, BSS has high reliability and bandwidth utilization in harsh scenarios. It can meet the high-quality requirements of cloud-aware MFC for transmission.

Development and performance test of CuCrZr/316 L explosive welding plate for EAST Lower divertor heat sink

As a key material for manufacturing EAST lower divertor heat sink, high-quality CuCrZr/316 L bonding plate is preferred to be manufactured by explosive welding, which is advantageous in zero input heat without deteriorating the material performance of CuCrZr and 316 L. In accordance with various detections and analyses of CuCrZr/316 L after the explosive welding: metallographic phase and electron microscope analysis showed the bonding interface contains no cavity or Cu/Fe metallic mutual dissolution; tensile stress of the bonding interface is higher than that of the CuCrZr material; a hollow heat sink sample (3 mm wall thickness) made of this material can withstand 4.5 MPa water pressure without deformation or leakage, and has been successfully undergone helium leak detection (200℃, 1 MPa, 1 × 10−11 m3/s). Such test results showed the bonding plate by explosive welding met all high quality requirements on fusion engineering that it can be applied to EAST divertor reliably.

Artificial intelligence with neural networks in optical measurement and inspection systems

Abstract Optical measuring and inspection systems play an important role in automation as they allow a comprehensive and non-contact quality assessment of products and processes. In this field, too, systems are increasingly being used that apply artificial intelligence and machine learning, mostly by means of artificial neural networks. Results achieved with this approach are often very promising and require less development effort. However, the supplementation and replacement of classical image processing methods by machine learning methods is not unproblematic, especially in applications with high safety or quality requirements, since the latter have characteristics that differ considerably from classical image processing methods. In this paper, essential aspects and trends of machine learning and artificial intelligence for the application in optical measurement and inspection systems are presented and discussed.

Lack of tightness analysis of concealed welded radiators

Stainless steel X2CrNi18-9 (304L) radiators were analysed. During detailed examination we proved that tube overlap fillet joint was welded incorrectly and had leaks. Wrong designed jig, incorrect robot movements and non-central tubes position let mounted parts move during welding operation. Shrinkage of the weld caused the tubes to move relative to each other with the formation of a larger gap on one side. Lack of correction of the robot arm movement and fixed stick-out created inadequate fusion into the tube with a smaller cross-section.Identification of non-compliance based on standard NDT methods such as visual inspection, liquid or dye penetrant inspection or X-ray was not possible. Also, destructive methods such as high-pressure water test was not be able to show this type of defect.Only innovative HLT helium leak testing method was able to show non-compliance of the joint. Helium is the ideal element to detect micro cracks in weld as it is an insert gas made up to tiny atoms and has low viscosity, so little atoms can travel fast. This method has a very big potential in the welding industry as a precise and fast NDT test on highest quality requirements.

Toolpath Regeneration in Subregional Contour-Parallel Processing Based on Isoscallop Method

Advanced manufacturing technologies have made great progress in the fields of aerospace, resources, and power, and the complex curved surface parts with local rapidly varied geometric feature are increasingly and widely used. On account of the complex geometric feature for this kind of parts, global processing technology cannot meet the requirements of high quality and high-efficiency processing, and the subregional processing method is used. However, the existing methods usually lead to bad machining quality at the boundary and are also prone to form obvious machined trace at the center of machining region in subregional processing. Hence, in this article, a subregional toolpath regeneration method for contour-parallel processing based on the isoscallop method is proposed. First, the initial toolpath generation is finished, which can ensure machining quality at the boundary. Then, establishing the arc length error calculation model for the innermost loop of toolpaths, the arc length error is averaged in the side-step direction and the feeding direction by modifying the cutter contact points. Finally, the toolpath regeneration is realized, which can reduce machined trace at the center of machining region. Experimental results show that with the proposed method, the profile arithmetic average error and the maximum of profile deviation decrease by 32.03% and 53.38%, respectively, at the innermost loop of toolpaths compared with the results of the conventional isoscallop method. For that, the proposed method can improve the machining quality effectively for complex curved surface in subregional contour-parallel processing.

Research on Radar Servo Control System Based on Neuron Adaptive PID Control

Due to the fixed control parameters, traditional proportional integral differential (PID) control tend to have problems such as large overshoot, poor stability and low control accuracy, which is difficult to meet the high control quality requirement of modern radar servo system. In this paper, based on the neural network adaptive control theory, a radar servo control system is designed and its effect is improved through the self-learning of neurons, the adjustment of the weighting coefficient and the optimization of the PID controller parameters. The simulation results show that the radar servo control system using neuron adaptive PID control preforms faster response speed and higher control accuracy, which is obviously better than the system with traditional PID control.

Preparation and Properties of Spherical Mo Powders by Plasma Rotating Electrode Process for Additive Manufacturing

Since molybdenum has very high melting point of 2620 °C, there are many difficulties in its forming and post-processing, especially for deep processing. Furthermore as molybdenum is expensive, the utilization rate is important for the molybdenum processing. Additive manufacturing can directly manufacture the parts without mold and increase the utilization rate, and brings an opportunities for the new direction of deep processing for molybdenum. Due to the high quality requirements of molybdenum powder in additive manufacturing technology, the high-quality spherical molybdenum powder was prepared by plasma rotating electrode process method in the present study. The morphology, particle size and particle size distribution, chemical and physical properties were investigated. The molybdenum powder prepared by plasma rotating electrode process method showed to have high purity, high sphericity, good fluidity and high bulk density, proper particle size distribution and low gap element within the powder. The microstructure of the powder was a mixed structure of dendrites and cell crystals formed by rapid solidification, and as the particle size of the powder gradually decreased, the microstructure of the powder surface was remarkably refined. Within a certain range, the molybdenum powder with a wide particle size distribution had better fluidity and higher bulk density. The high-quality spherical molybdenum powder was prepared by plasma rotating electrode process method, which can meet the requirements of additive manufacturing technology for powder material performance.

Modeling QoE for Buffered Video Streaming in Interference-Limited Cellular Networks

Mobile networks have to cope with an ever increasing demand for video streaming, an application that imposes high quality requirements for user satisfaction. In this paper, we present an analytical model to calculate two important quality measures for streaming traffic, namely the video startup delay distribution and the buffer starvation probability. The queuing-theoretic model differs from related work by incorporating data flow dynamics of the considered cell, as well as the dynamics of fluctuating interference from neighboring cells, with the goal of accurately representing a multi-cellular environment. In this regard, we propose a finite-volume method to approximate the solution of the involved system of partial differential equations, where other approaches from comparable work were faced with numerical problems. We also evaluate two simplified versions of the model, where only the interference dynamics or all coupling terms are omitted, respectively. The model allows us to study the impact of different parameters on buffered video streaming performance. Additionally, we propose a user-centric metric to measure quality of experience (QoE). To the best of our knowledge, our approach is novel and has not been covered by comparable work. The presented results can help to design future cellular networks with enhanced video streaming experience.

Rapid Prototyping : An Effective Tool for Manufacturing of Intricate Geometries of Automotive Components : A Case Study

Tooling is one of the most important elements in the manufacturing process. To achieve the high quality requirements, moulds are traditionally made by CNC-machining, electro-discharge machining or conventional technologies. The term Rapid Prototyping (RP) refers to a group of technologies that can automatically construct physical model from Computer Aided Design data. Rapid Prototyping allows them to be made quicker and less expensively. The Rapid Prototyping techniques involves basic five step process like, Create a 3D CAD model of the required design, Convert the CAD model to STL format, Slice the STL file, Construct the model Layer by Layer and finally Clean and finish the model. Rapid Prototyping is widely used in fabrication of intricate parts of automotive, aerospace, medical and consumer products industries. Also especially moulds are made from RP model from Rapid Tooling. In this paper, a case study of manufacturing of engine head is taken. In contrast to construction of models by machining, based on the removal of material until the required form is achieved, RP model is made by adding material layer by layer until the whole part will be completed.

Application of the marketing mix to the world export of animal products

Agricultural trade is complicated owing to perishable goods and high requirements for safety and quality, especially by animal products. Intensifying their exports is a major priority in the context of augmenting competitive negotiations and providing global food security to cover a shortage of an animal protein intake. To address such challenges, this study aimed at improving marketing performance necessary for developing the world exports of animal products. The methodological research framework was the Marketing Mix model, which included Product, Price, Place, and Promotion, and was amplified by Innovation. The model components were presented by the average export prices and indicators for Infrastructure, ICT adoption, and Innovation capability evaluated for each exporting country. For testing hypotheses about homo- and heterogeneity of top exporters, this research utilized the single factor Analysis of Variance (ANOVA) technique. The offered approach was applied to the most valuable export segments of poultry, livestock, and dairy world markets. They engaged from 75 to 140 countries and had total export values between USD 3.2 billion and USD 33.2 billion. The study outcomes captured similarities and differences of Price, Place, Promotion, and Innovation components among the First 10, Second 10, and Third 10 ranked exporters. Given the found indicators of the top world exporters, the study clarifies prospects and attainable goals on developing exports of animal products at a country level.

The use of modified vegetable oil from Crambe abyssinica as a lubricant base for the food industry

Abstract Lubricants that are based on vegetable oils and other renewable resources are the subject of many research studies and can be used in various applications, especially in the food industry, which is characterized by the high quality requirements related to the necessity to develop biodegradable lubricants that are environmentally friendly and do not contain harmful components and are safe to use for people. The objective of the described research was to obtain a base oil with a certain viscosity, which is higher than the viscosity of the initial vegetable oil, and certain lubricating properties. The initial oil derived from Crambe abyssinica was subjected to oxidation in the presence of N-hydroxyphthalimide with or without supercritical CO2 as a solvent. As a final result of this study, base oils meeting the viscosity requirements and having high biodegradability were obtained. The Raman spectra of the modified vegetable oils were evaluated and they were used for the initial assessment of the composition and the evaluation of the presence of harmful chemical compounds.

Innovative technologies in construction

The article considers theoretical and practical bases of tendencies of development of construction market of Ukraine; determined that the directions of innovative business in construction are the following: a) the purchase of advanced foreign technologies and the organization of production of new products; b) purchase of progressive materials, machines and equipment for construction organizations; c) purchase of domestic and foreign patents for further organization of own production of building materials; d) services of foreign construction companies in the production of construction works using new technologies; e) conducting own R&D; f) implementation of own innovative architectural and design developments; g) training of workers and specialists in new technologies, skills in working with new mechanisms and building materials. Conclusions have been made about the need to introduce innovative technologies in construction; directions for stimulating the development of the construction market based on the introduction of innovative technologies are proposed. It is determined that in recent years there have been global changes in the main economic and production indicators of the external environment that affect the activity of construction enterprises. The most important of them are: complication of production; high requirements for quality of products and terms of delivery of products to customers; the emergence of individual requirements for products, which necessitated the transition to almost individual production with the whole complex of complex organizational and technical measures and system of reorganizations; increased competition.It is substantiated that the implementation of the stated proposals for the activation of innovative activity in construction can serve as a certain impetus for accelerating the scientific and technological development of the domestic economy, the development not only of the construction market, but also the enhancement of Ukraine's competitiveness in the world market, which is especially relevant in modern conditions