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How does working from home affect developer productivity?——A case study of Baidu during the COVID-19 pandemic

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Science China(Information Sciences) 2022年第4期65卷 141-155页

作者： lingfeng BAO Tao li Xin XIA Kaiyu ZHU Hui li xiaohu YANG College of Computer Science and Technology Zhejiang University Baidu Inc. Faculty of Information Technology Monash University

Nowadays, working from home(WFH) has become a popular work arrangement due to its many potential benefits for both companies and employees(e.g., increasing job satisfaction and retention of employees). Many previous studies have investigated the impact of WFH on the productivity of employees.However, most of these studies usually use a qualitative analysis method such as surveys and interviews,and the studied participants do not work from home for a long continuing time. Due to the outbreak of coronavirus disease 2019(COVID-19), a large number of companies asked their employees to work from home, which provides us an opportunity to investigate whether WFH affects their productivity. In this study, to investigate the difference in developer productivity between WFH and working onsite, we conduct a quantitative analysis based on a dataset of developers’ daily activities from Baidu Inc., one of the largest IT companies in China. In total, we collected approximately four thousand records of 139 developers’ activities of 138 working days. Out of these records, 1103 records are submitted when developers work from home due to the COVID-19 pandemic. We find that WFH has both positive and negative impacts on developer productivity in terms of different metrics, e.g., the number of builds/commits/code reviews. We also notice that WFH has different impacts on projects with different characteristics including programming language,project type/age/size. For example, WFH has a negative impact on developer productivity for large projects.Additionally, we find that productivity varies for different developers. Based on these findings, we get some feedback from developers of Baidu and understand some reasons why WFH has different impacts on developer productivity. We also conclude several implications for both companies and developers.

关键词： WFH developer productivity Developer Productivity

(DarkAI)Mapping the large-scale density field of dark matter using artificial intelligence

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Science China(Physics,Mechanics & Astronomy) 2024年第1期67卷 143-159页

作者： Zitong Wang Feng Shi xiaohu Yang Qingyang li Yanming liu Xiaoping li School of Aerospace Science and Technology Xidian UniversityXi’an 710126China Department of Astronomy School of Physics and Astronomyand Shanghai Key Laboratory for Particle Physics and CosmologyShanghai Jiao Tong UniversityShanghai 200240China Tsung-Dao Lee Institute and Key Laboratory for Particle Physics Astrophysics and CosmologyMinistry of EducationShanghai Jiao Tong UniversityShanghai 200240China Institute for Astronomy University of EdinburghRoyal ObservatoryEdinburgh EH93HJUnited Kingdom

Herein,we present a deep-learning technique for reconstructing the dark-matter density field from the redshift-space distribution of dark-matter halos.We built a UNet-architecture neural network and trained it using the COmoving Lagrangian Acceleration fast simulation,which is an approximation of the N-body simulation with 5123 particles in a box size of 500 h^(-1)Mpc.Further,we tested the resulting UNet model not only with training-like test samples but also with standard N-body simulations,such as the Jiutian simulation with 61443particles in a box size of 1000 h^(-1)Mpc and the ELUCID simulation,which has a different cosmology.The real-space dark-matter density fields in the three simulations can be reconstructed reliably with only a small reduction of the cross-correlation power spectrum at 1%and 10%levels at k=0.1 and 0.3 h Mpc-1,respectively.The reconstruction clearly helps to correct for redshift-space distortions and is unaffected by the different cosmologies between the training(Planck2018)and test samples(WMAP5).Furthermore,we tested the application of the UNet-reconstructed density field to obtain the velocity&tidal field and found that this approach provides better results compared with the traditional approach based on the linear bias model,showing a 12.2%improvement in the correlation slope and a 21.1%reduction in the scatter between the predicted and true velocities.Thus,our method is highly efficient and has excellent extrapolation reliability beyond the training set.This provides an ideal solution for determining the three-dimensional underlying density field from the plentiful galaxy survey data.

关键词： dark matter large-scale structure cosmology

Energy consumption optimization for edge computing-supported cellular networks based on optimal transport theory

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Science China(Information Sciences) 2024年第2期67卷 201-218页

作者： Xiangyu LV xiaohu GE Yi ZHONG Qiang li Yong XIAO School of Electronic Information and Communications Huazhong University of Science and Technology

With advancements in mobile communication technologies, there have been multiple user device(UD) connections to cellular networks. Because of changes in the spatial distribution of UDs and application requirements, the traditional offloading mechanism based on the nearest distance will result in heavy loads for some base stations(BSs). Because there is a high-order relationship between the energy consumption of the BS processing tasks and the number of computing tasks, the traditional offloading mechanism will result in high energy consumption, and UD’s offloading decision must be dynamically adjusted. The offloading decision of UDs is optimized based on detailed information about various parameters associated with a network from the standpoint of distribution. This information includes details regarding the spatial distribution of UDs,application requirements, and the offloading period of computing tasks. Based on optimal transport theory,an energy consumption optimization algorithm is suggested to lower the total amount of energy consumed by the offloading process of UDs’ computing tasks by reasonably planning the offloading BSs of the UDs in the networks. The simulation results show that the proposed offloading mechanism based on energy consumption optimization reduces the total energy consumption of the offloading process by 28.09% when compared to the traditional offloading mechanism, and the traffic managed by each BS is balanced.

关键词： optimal transport theory edge computing energy consumption reduction dynamic voltage frequency scaling

Observation-Driven Multiple UAV Coordinated Standoff Target Tracking Based on Model Predictive Control

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Tsinghua Science and Technology 2022年第6期27卷 948-963页

作者： Shun Sun Yu liu Shaojun Guo Gang li xiaohu Yuan Department of Control Science and Technology Naval Aviation UniversityYantai 264001China Department of Electronic Engineering Tsinghua UniversityBeijing 100084China National Institute of Defense Technology Innovation Academy of Military Sciences PLABeijing 100091China Department of Automation Tsinghua UniversityBeijing 100084China

An observation-driven method for coordinated standoff target tracking based on Model Predictive Control(MPC)is proposed to improve observation of multiple Unmanned Aerial Vehicles(UAVs)while approaching or loitering over a target.After acquiring a fusion estimate of the target state,each UAV locally measures the observation capability of the entire UAV system with the Fisher Information Matrix(FIM)determinant in the decentralized architecture.To facilitate observation optimization,only the FIM determinant is adopted to derive the performance function and control constraints for coordinated standoff tracking.Additionally,a modified iterative scheme is introduced to improve the iterative efficiency,and a consistent circular direction control is established to maintain long-term observation performance when the UAV approaches its target.Sufficient experiments with simulated and real trajectories validate that the proposed method can improve observation of the UAV system for target tracking and adaptively optimize UAV trajectories according to sensor performance and UAV-target geometry.

关键词： coordinated tracking standoff tracking observation-driven Model Predictive Control(MPC) multiple UAVs Fisher Information Matrix(FIM)

THE BLACK RIVER BRIDGE BRINGING PROSPERITY TO LOCALS

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China's Tibet 2019年第3期30卷 38-41页

作者： LI Xiaohu 不详

In the past, people always crossed the river by boat and would risk their lives doing it,' says Norbu Tashi, a villager from Xia in the town of Nenwa, Zoige County, as he observes the new Nenwa-Xiaman Bridge.'People have benefited a lot from this new bridge. It’s more convenient for cows, sheep, horses, and people to cross over, and it saves us trouble and worry while we’re busy going about our daily lives.

关键词： THE BLACK RIVER BRIDGE BRINGING PROSPERITY TO LOCALS

A case study of blasting vibration attenuation based on wave component characteristics

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第5期15卷 1298-1311页

作者： Chong Yu Haibo li Haozhen Yue xiaohu Wang Xiang Xia State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China

A typical blasting vibration wave is a composite wave,and its attenuation law is affected by the type of dominant wave component.The purpose of the present study is to establish an attenuation equation of the peak particle velocity(PPV),taking into account the attenuation characteristics of P-,S-and R-waves in the blasting vibration wave.Field blasting tests were carried out as a case to specifically apply the proposed equation.In view of the fact that the discrete properties of rock mass will inevitably cause the uncertainty of blasting vibration,we also carried out a probability analysis of PPV uncertainty,and introduced the concept of reliability to evaluate blasting vibration.The results showed that the established attenuation equation had a higher prediction accuracy,and can be considered as a promising equation implemented on more complex sites.The adopted uncertainty analysis method can comprehensively take account of the attenuation law of blasting vibration measured on site and discrete properties of rock masses.The obtained distribution of the PPV uncertainty factor can quantitatively evaluate the reliability of blasting vibration,which is a powerful and necessary supplement to the PPV attenuation equation.

关键词： Blasting vibration Wave component Field blasting tests Attenuation equation Uncertainty analysis Bayesian theory

A Stochastic Model on One-Unit Repairable Systems with Multiple Degenerative States

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Journal of Systems Science & Complexity 2018年第3期31卷 804-819页

作者： LI Xiaohu DING Weiyong Department of Mathematical Sciences Stevens Institute of Technology Hoboken NJ 07030 USA School of Mathematics and Statistics Jiangsu Normal University Xuzhou 221116 China

这份报纸为有多重失败的退化系统基于比例的危险和比例的颠倒的危险模型说的一个一个单位学习一个维护模型。作者调查怎么参数影响操作的系统配置和修理乘和因此系统性能的变化。而且，作者也每统一时间为长期间平均支出导出明确的表示... 详细信息

这份报纸为有多重失败的退化系统基于比例的危险和比例的颠倒的危险模型说的一个一个单位学习一个维护模型。作者调查怎么参数影响操作的系统配置和修理乘和因此系统性能的变化。而且，作者也每统一时间为长期间平均支出导出明确的表示。在一个更新周期定位修理的最佳的数字的一个算法也被讨论。

关键词：退化系统维护模型修理单位多重随机危险模型参数影响

Influence factors of methane hydrate formation from ice:Temperature,pressure and SDS surfactant

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Chinese Journal of Chemical Engineering 2019年第2期27卷 405-410页

作者： Weiguo liu Yanghui li xiaohu Xu Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology

A series of experiments of forming hydrate from ice powders in different conditions have been carried out with constant volume method to evaluate the influence factors such as pressure, temperature, and SDS surfactant. The change of temperature and pressure were collected as a function of elapsed time, which were used to calculate the gas consumption and hydrate saturation during hydrate formation(pVT method). Based on the experimental results and the analysis, it is concluded that:(1) Both initial pressure and temperature have effect on the hydrate formation and temperature plays a more important role in the process;(2) heating and secondary pressurization will promote the gas hydrate formation and enhance the hydrate saturation as a result. Meanwhile, the promotion of heating seems to be more obvious than that of secondary pressurization;(3) different concentrations of SDS surfactant have clearly influence on the saturation of gas hydrate and there is an optimal concentration to promote the hydrate formation.

关键词： Methane hydrate Ice Heating Secondary pressurization Surfactant

Biocompatible Poly(ε-caprolactone)-based Shape-memory Polyurethane Composite Scaffold with Bone-induced Activity

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Journal of Bionic Engineering 2022年第1期19卷 167-178页

作者： Kun Luo li Wang xiaohu Chen Xiyang Zeng Shiyi Zhou Peicong Zhang Junfeng li College of Materials Chemistry and Chemical EngineeringChengdu University of TechnologyChengdu610059China

3D porous scaffold could provide suitable bone-like structure for cell adhesion and proliferation;however,surgical suffering from large volume implantation is a great challenge for patients.In this study,a shape programmable porous poly(ε-caprolactone)(PCL)-based polyurethane scaffold with memory effect was synthesized via gas foaming method,using Citrate modified Amorphous calcium Phosphate(CAP)as bioactive factor.The bending experiments indicated that the scaffolds achieved excellent shape-memory effect,which could be influenced by particle weight content.In vitro mineralization results suggested that the deposition of hydroxyapatite was promoted by scaffolds.Additionally,cell assay showed that composite scaffolds presented good cell toxicity and osteogenicity by the differentiation of rat Mesenchymal Stem Cells(rMSCs)into the osteogenic lineage.In the model of rat cranial implantation,the reparative tissue covered the defect site and bone-like structure deposited on the scaffold due to the formation of new bones.In summary,the porous smart shape-memory composite scaffolds could be a potential candidate in future distinctive bone repair applications.

关键词： Porous scaffolds Bone repair Shape-memory polyurethane Amorphous calcium phosphate Biocompatibility