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Improving Fault Detection in Modified Code-A Study from the Telecommunication Industry

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Journal of Computer Science & Technology 2007年第3期22卷 397-409页

作者： Piotr Tomaszewski lars Lundberg Hkan Grahn School of Engineering Blekinge Institute of Technology SE-372 25 RonnebySweden

Many software systems are developed in a number of consecutive releases. In each release not only new code is added but also existing code is often modified. In this study we show that the modified code can be an important source of faults. Faults are widely recognized as one of the major cost drivers in software projects. Therefore, we look for methods that improve the fault detection in the modified code. We propose and evaluate a number of prediction models that increase the efficiency of fault detection. To build and evaluate our models we use data collected from two large telecommunication systems produced by Ericsson. We evaluate the performance of our models by applying them both to a different release of the system than the one they are built on and to a different system. The performance of our models is compared to the performance of the theoretical best model, a simple model based on size, as well as to analyzing the code in a random order （not using any model）. We find that the use of our models provides a significant improvement over not using any model at all and over using a simple model based on the class size. The gain offered by our models corresponds to 38-57% of the theoretical maximum gain.

关键词： fault prediction metrics testing and debugging

Real-time performance of DAE and ODE based estimators evaluated on a diesel engine

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Science China(Information Sciences) 2018年第7期61卷 27-39页

作者： Erik H?CKERDAL Erik FRISK lars ERIKSSON Scania CV AB Vehicular Systems Link?ping University

Computation and sampling time requirements for real-time implementation of observers is studied. A common procedure for state estimation and observer design is to have a system model in continuous time that is converted to sampled time with Euler forward method and then the observer is designed and implemented in sampled time in the real time system. When considering state estimation in real time control systems for production there are often limited computational resources. This becomes especially apparent when designing observers for stiff systems since the discretized implementation requires small step lengths to ensure stability. One way to reduce the computational burden, is to reduce the model stiffness by approximating the fast dynamics with instantaneous relations, transforming an ordinary differential equations(ODE)model into a differential algebraic equation(DAE) model. Performance and sampling frequency limitations for extended Kalman filter(EKF)'s based on both the original ODE model and the reduced DAE model are here analyzed and compared for an industrial system. Furthermore, the effect of using backward Euler instead of forward Euler when discretizing the continuous time model is also analyzed. The ideas are evaluated using measurement data from a diesel engine. The engine is equipped with throttle, exhaust gas recirculation(EGR), and variable geometry turbines(VGT) and the stiff model dynamics arise as a consequence of the throttle between two control volumes in the air intake system. The process of simplifying and modifying the stiff ODE model to a DAE model is also discussed. The analysis of the computational effort shows that even though the ODE, for each time-update, is less computationally demanding than the resulting DAE, an EKF based on the DAE model achieves better estimation performance than one based on the ODE with less computational effort. The main gain with the DAE based EKF is that it allows increased step lengths without degrading the

关键词： estimation learning DAE ODE EKF observability real-time

Towards Accurate Bit Error Simulation in Wireless Sensor Networks Including Environmental Influences

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Journal of Computer Science & Technology 2020年第4期35卷 809-824页

作者： Sven Pullwitt Robert Hartung Ulf Kulau lars Wolf Institute for Operating Systems and Computer Networks Technische Universitat BraunschweigBraunschweig 38106 Germany

Simulation is a common technique for the evaluation of new approaches and protocols in networked systems and provides many ***,it is also well known that the relevance of the simulation results for real-world applications depends on the various models which are used within the simulation,e.g.,for the characteristics of the radio *** this paper,we introduce the Extended Multipath Raytracing Model,an extension to the ray-tracing radio medium available in Cooja,to improve the modelling of wireless links in simulated Wireless Sensor *** extension allows the simulation of environmental influences onto links on a per node basis,allowing the analysis of various effects observed in experiments in a virtual ***,the packet-based modelling of transmission errors is extended to provide the simulation of bit errors,allowing new usage scenarios,like the simulation of error detection and Forward Error Correction codes in Cooja.

关键词： bit error Contiki Cooja environmental influence simulation wireless sensor network

Prevalence of Charles Bonnet syndrome in low vision:a systematic review and meta-analysis

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Annals of Eye Science 2022年第2期7卷 80-92页

作者： Yousif Subhi Mads Assenholt Nielsen Daniel Andrew Richard Scott lars Morten Holm Amardeep Singh Department of Ophthalmology RigshospitaletGlostrupDenmark Department of Clinical Research University of Southern DenmarkOdenseDenmark Faculty of Health and Medical Sciences University of CopenhagenKøbenhavnDenmark Department of Ophthalmology Waikato District Health BoardHamiltonNew Zealand

Background:Charles Bonnet syndrome(CBS)is characterized by vivid lifelike visual hallucinations and is typically seen in individuals with visual *** this systematic review,we summarize current knowledge on the prevalence of CBS in patients with low ***:We searched 11 literature databases on 21 April 2021 for studies on the prevalence of CBS in low vision *** protocol was registered in the PROSPERO database(***42021255021).Eligible studies were defined as those on a population of low vision patients wherein the prevalence of CBS was evaluated(without any further restriction on the method for diagnosis of CBS).No restriction was enforced on study design,but we expected observational cross-sectional studies due to the nature of our research *** authors independently extracted data and evaluated risk of bias of individual studies using the Agency for Healthcare Research and Quality checklist for cross-sectional *** underwent qualitative review in the text and quantitatively in a prevalence meta-analysis using the random-effects *** analysis was made to evaluate the robustness of the summary ***:We identified 11 studies,which summarized data on 4,521 individuals with visual *** of CBS was based on screening questions or interviews,which in positive cases often was explored in more detail with follow-up questions or *** studies either had normal mental state as a participant eligibility criterion or as a part of the diagnosis of *** pooled prevalence of CBS in low vision patients aged≥40 years was 19.7%(95%CI:13.8%to 26.4%).The sensitivity analysis showed certain robustness in the summary prevalence estimate wherein prevalence estimates ranged from 16.9%to 22.5%.Conclusions:CBS is a prevalent condition in patients with low vision at a rate of approximately one in five *** that an estimated 239 million individuals have moderate visual im

关键词： Charles Bonnet syndrome(CBS) visual hallucinations low vision

Surface integral analogy approaches for predicting noise from 3D high-lift low-noise wings

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Acta Mechanica Sinica 2014年第3期30卷 326-338页

作者： Hua-Dong Yao lars Davidson lars-Erik Eriksson Shia-Hui Peng Olof Grundestam Peter E.Eliasson Department of Applied Mechanics Chalmers University of Technology Department of Aeronautics and Systems Technology Swedish Defence Research Agency (FOI)

Three surface integral approaches of the acoustic analogies are studied to predict the noise from three concep- tual configurations of three-dimensional high-lift low-noise wings. The approaches refer to the Kirchhoff method, the Ffowcs Williams and Hawkings （FW-H） method of the permeable integral surface and the Curle method that is known as a special case of the FW-H method. The first two approaches are used to compute the noise generated by the core flow region where the energetic structures exist. The last approach is adopted to predict the noise specially from the pressure perturbation on the wall. A new way to con- struct the integral surface that encloses the core region is proposed for the first two methods. Considering the local properties of the flow around the complex object-the actual wing with high-lift devices-the integral surface based on the vorticity is constructed to follow the flow structures. The surface location is discussed for the Kirchhoff method and the FW-H method because a common surface is used for them. The noise from the core flow region is studied on the basis of the dependent integral quantities, which are indicated by the Kirchhoff formulation and by the FW-H formulation. The role of each wall component on noise contribution is analyzed using the Curle formulation. Effects of the volume integral terms of Lighthill＇s stress tensors on the noise pre-diction are then evaluated by comparing the results of the Curle method with the other two methods.

关键词： Aero-acoustics High-lift facilities Surface integral approaches of acoustic analogy

Necessity of structural rearrangements for O-O bond formation between O5 and W2 in photosystemⅡ

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Journal of Energy Chemistry 2021年第6期30卷 436-442,I0011页

作者： Yu Guo Biaobiao Zhang lars Kloo Licheng Sun Department of Chemistry School of Engineering Sciences in ChemistryBiotechnology and HealthKTH Royal Institute of Technology.S E-10044 StockholmSweden State Key Laboratory of Fine Chemicals Institute of Artificial PhotosynthesisDUT-KTH Joint Education and Research Center on Molecular DevicesDalian University of Technology(DUT)Dalian 116024LiaoningChina Center of Artificial Photosynthesis for Solar Fuels School of ScienceWestlake University.Hangzhou 310024ZhejiangChina

Numerous aspects of the water oxidation mechanism in photosystemⅡhave not been fully elucidated,especially the O-O bond formation ***,a body of experimental evidences have identified the O5 and W2 ligands of the oxygen-evolving complex as the highly probable substrate *** this work,we studied O-O bond formation between O5 and W2 based on the native Mn4 Ca cluster by density functional *** rearrangements before the formation of the S_(4) state were found as a prerequisite for O-O bond formation between O5 and W2,regardless if the suggested pathways involving the typical Mnl(Ⅳ)-O·species or the recently proposed Mn4(Ⅶ)(O)2 *** alternatives for the S2→S_(3) and S_(3)→S_(4) transitions accounting for such required rearrangements are *** findings reflect that the structural flexibility of the Mn4 Ca cluster is essential to allow structural rearrangements during the catalytic cycle.

关键词： Density functional theory Oxygen-evolving complex Substrate water OAO bond formation Structural rearrangement

Predisposing factors for atrial fibrillation in the elderly

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Journal of Geriatric Cardiology 2017年第3期14卷 179-184页

作者： Kristina Wasmer lars Eckardt Gunter Breithardt Division of Electrophysiology Department of Cardiovascular Medicine University Hospital Miinster Germany

Atrial fibrillation (AF) in the elderly occurs as a consequence of cardiovascular aging and an age related increase of comorbidity. Several predisposing factors for AF have been identified for the overall AF population. Most of them, cardiovascular disease in particular, play a role in younger and older patients. The longer time period during which these risk factors can cause structural changes that ultimately lead to AF may, at least in part, explain the association between age and AF. In addition, less well defined age-related changes in cellular electrophysiologic properties and structure predispose to AF in the elderly.

关键词：诱发因素老年人颤动心房心血管疾病年龄相关结构变化生理学特性

Effective and Sustainable Flood and Landslide Risk Reduction Measures:An Investigation of Two Assessment Frameworks

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International Journal of Disaster Risk Science 2016年第4期7卷 374-392页

作者： Yvonne Andersson-Skld lars Nyberg Swedish National Road and Transport Research Institute(VTI) Centre for Climate and Safety Karlstad University

Natural events such as floods and landslides can have severe *** risks are expected to increase,both as a consequence of climate change and due to increased vulnerabilities,especially in urban *** preventive measures are often cost-effective,some measures are beneficial to certain values,while some may have negative impacts on other *** aim of the study presented here was to investigate two frameworks used for assessing the effectiveness and sustainability of physical and nonphysical flood and landslide risk reduction *** study is based on literature,available information from authorities and municipalities,expert knowledge and experience,and stakeholder views and *** results indicate that the risks for suboptimization or maladaptation are reduced if many aspects are included and a broad spectrum of stakeholders are *** sustamability assessment tools applied here can contribute to a more transparent and sustainable risk management process by assessing strategies and interventions with respect to both short- and long-term perspectives,including local impacts and wider environmental impacts caused by climate change,for *** tools can also cover social and economic *** assessment tools provide checklists that can support decision processes,thus allowing for more transparent decisions.

关键词： Flood risk Landslide risk Risk reduction measures Sustainability assessment tools Sweden

Z charmoniumlike mesons

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Chinese Physics C 2011年第7期35卷 695-702页

作者： Arafat Gabareen Mokhtar Stephen lars Olsen SLAC National Accelerator Laboratory Stanford Seoul National University KOREA

A brief review of the experimental situation concerning the electrically charged charmoniumlike meson candidates, Z-, is presented.

关键词： quarkonium exotics multiquark state