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Tsinghua Science and Technology 2019年第4期24卷 423-434页

作者： Qing Sun Ji Wu Wenge Rong Wenbo Liu the School of Computer Science and Engineering BeihangUniversity

In programming courses, the traditional assessment approach tends to evaluate student performance by scoring one or more project-level summative assignments. This approach no longer meets the requirements of a quality programming language education. Based on an upgraded peer code review model, we propose a formative assessment approach to assess the learning of computer programming languages, and develop an online assessment system(OOCourse) to implement this approach. Peer code review and inspection is an effective way to ensure the high quality of a program by systematically checking the source code. Though it is commonly applied in industrial and open-source software development, it is rarely taught and practiced in undergraduate-level programming courses. We conduct a case study using the formative assessment method in a sophomore level Object-Oriented Design and Construction course with more than 240 students. We use Moodle(an online learning system) and some relevant plugins to conduct peer code review. We also conduct data mining on the running data from the peer assessment activities. The case study shows that formative assessment based on peer code review gradually improved the programming ability of students in the undergraduate class.

关键词： peer code review programming language learning dynamic designation formative assessment

A numerical modelling approach to assess the behaviour of underground cavern subjected to blast loads

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International Journal of Mining Science and Technology 2018年第6期28卷 975-983页

作者： Saikat Kuili Vedala Rama Sastry Department of Civil Engineering National Institute of Technology Karnataka Department of Mining Engineering National Institute of Technology Karnataka

The paper gives an insight into the behaviour of large underground caverns which are subjected to blast loads. Caverns are generally constructed in hard rock formation which compels us to use blasting methods for the excavation works. Comparative study was done between models with intact rock mass and discontinuities to assess the stability of cavern as a result of blast loads. Numerical modelling was performed with 3 dimensional distinct element code(3 DEC) to analyse the performance of cavern walls in terms of displacement and to compute peak particle velocities(PPV) both around the cavern periphery and at surface of models. Results showed that the velocity wave with higher frequency exhibited large displacements around the periphery of cavern. Computation of PPV showed that model with horizontal joint sets showed lower PPV in comparison to model with intact rock mass. PPV values were also analysed on the surface for model consisting vertical joints spaced at 4 m intervals. Comparative study of PPV on surface vertically above the blast location between models with horizontal joints spaced at 4 m and vertical joints at 4 m intervals were conducted. Results depicted higher magnitudes of PPV for model with vertical joints in comparison to model with horizontal joints.

关键词： Large underground caverns Hard rock formation Numerical modelling 3 dimenssional distinct element code Peak particle velocities

Epigenetic and non-epigenetic mode of SIRT1 action during oocyte meiosis progression

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Journal of Animal Science and Biotechnology 2019年第4期10卷 895-906页

作者： Jan Nevoral Lukas Landsmann Miriam Stiavnicka Petr Hosek Jiri Moravec Sarka Prokesova Hedvika Rimnacova Eliska Koutna Pavel Klein Kristyna Hoskova Tereza Zalmanova Tereza Fenclova Jaroslav Petr Milena Kralickova Biomedical Center Faculty of Medicine in PilsenCharles Universityalej Svobody 1655/7632300 PilsenCzech Republic Department of Histology and Embryology Faculty of Medicine in PilsenCharles UniversityKarlovarska 4830166 PilsenCzech Republic Faculty of Science Charles UniversityAlbertov 2038/612800 PragueCzech Republic Faculty of Agriculture Food and Natural ResourcesCzech University of Life Sciences in PragueKamycka 12916500 Praha-SuchdolCzech Republic Institute of Animal Science Pratelstvi 815/10710400Prague 10-UhrinevesCzech Republic

Background: SIRT1 histone deacetylase acts on many epigenetic and non-epigenetic targets. It is thought that SIRT1 is involved in oocyte maturation;therefore, the importance of the ooplasmic SIRT1 pool for the further fate of mature oocytes has been strongly suggested. We hypothesised that SIRT1 plays the role of a signalling molecule in mature oocytes through selected epigenetic and non-epigenetic regulation.Results: We observed SIRT1 re-localisation in mature oocytes and its association with spindle microtubules.In mature oocytes, SIRT1 distribution shows a spindle-like pattern, and spindle-specific SIRT1 action decreasesα-tubulin acetylation. Based on the observation of the histone code in immature and mature oocytes, we suggest that SIRT1 is mostly predestined for an epigenetic mode of action in the germinal vesicles(GVs) of immature oocytes. Accordingly, BML-278-driven trimethylation of lysine K9 in histone H3 in mature oocytes is considered to be a result of GV epigenetic transformation.Conclusions: Taken together, our observations point out the dual spatiotemporal SIRT1 action in oocytes,which can be readily switched from the epigenetic to non-epigenetic mode of action depending on the progress of meiosis.

关键词： Epigenetics Histone code In vitro maturation Oocyte SIRT1 Sirtuin 1

Evaluation of plow system performance in long-wall mining method using particle flow code

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International Journal of Coal Science & Technology 2019年第4期6卷 518-535页

作者： Mohammadreza Ajamzadeh Vahab Sarfarazi Hesam Dehghani Hamedan University of Technology HamedanIran

The underground or open-pit methods are used for the extraction of mineral resources,each of which is divided into different categories.Coal is one of the mineral resources,which is exploited either by the surface or the underground methods.The long-wall mining is one of the methods for the underground coal mining.In this method,which is a mechanized one,some machines such as the shearer or plow are used for the mining.The coal mine in Parvadeh,Tabas is a mechanized mine that is extracted by the long-wall mining.The modeling with particle flow code software was used in this mine for the evaluation of plow performance using the coal specifications.In this regard,the sample was first calibrated by sampling from the Parvadeh coal mine and performing the uniaxial and Brazilian tests on the model.Then,the modeling was done by constructing the model and using the variables such as the clearance angle and the linear velocity of the plow.After making 28 models for the plow,the best model of the plow was selected based on the maximum force applied to the machine in the X direction.Finally,the results of this study showed that the best plow performance is for a model with the clearance angle of zero and the linear velocity of 9 mm/min,and the maximum force applied to this model is equal to 39,000 kN in the X direction.

关键词： Plow Long-wall mining Particle flow code Numerical modeling

CRL： Efficient Concurrent Regeneration codes with Local Reconstruction in Geo-Distributed Storage Systems

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Journal of Computer Science & Technology 2018年第6期33卷 1140-1151页

作者： Quan-Qing Xu Wei-Ya Xi Khai Leong Yong Chao Jin Institute of High Performance Computing Agency for Science Technology and Research Singapore 138632 Singapore Data Storage Institute Agency for Science Technology and Research Singapore 138632 Singapore Institute for Infocomm Research Agency for Science Technology and Research Singapore 138632 Singapore

As a typical erasure coding choice, Reed-Solomon （RS） codes have such high repair cost that there is a penaltyfor high reliability and storage efficiency, thereby they are not suitable in geo-distributed storage systems. We present anovel family of concurrent regeneration codes with local reconstruction （CRL） in this paper. The CRL codes enjoy threebenefits. Firstly, they are able to minimize the network bandwidth for node repair. Secondly, they can reduce the numberof accessed nodes by calculating parities from a subset of data chunks and using an implied parity chunk. Thirdly, they arefaster than existing erasure codes for reconstruction in geo-distributed storage systems. In addition, we demonstrate howthe CRL codes overcome the limitations of the Reed-Solomon codes. We also illustrate analytically that they are excellent inthe trade-off between chunk locality and minimum distance. Furthermore, we present theoretical analysis including latencyanalysis and reliability analysis for the CRL codes. By using quantity comparisons, we prove that CRL（6, 2, 2） is only0.657x of Azure LRC（6, 2, 2）, where there are six data chunks, two global parities, and two local parities, and CRL（10,4, 2） is only 0.656x of HDFS-Xorbas（10, 4, 2）, where there are 10 data chunks, four local parities, and two global paritiesrespectively, in terms of data reconstruction times. Our experimental results show the performance of CRL by conductingperformance evaluations in both two kinds of environments： 1） it is at least 57.25% and 66.85% more than its competitorsin terms of encoding and decoding throughputs in memory, and 2） it has at least 1.46x and 1.21x higher encoding anddecoding throughputs than its competitors in JBOD （Just a Bunch Of Disks）. We also illustrate that CRL is 28.79% and30.19% more than LRC on encoding and decoding throughputs in a geo-distributed environment.

关键词： concurrent regeneration code local reconstruction geo-distributed storage system

Chemical speciation code CHEMSPEC and its applications

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Science China Chemistry 2009年第11期52卷 2020-2032页

作者： WANG XiangYun CHEN Tao LIU ChunLi Beijing National Laboratory for Molecular Sciences Department of Applied ChemistryCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China

The adsorption and migration behavior of a radionuclide in geological media heavily depends on its chemical forms in a given chemical environment.In order to predict the temporal and spatial distribution of radionuclides around a disposal site when its canister is damaged,it is necessary to develop coupled chemical speciation-solute transport models and relevant software.For that reason,we wrote a new chemical speciation program CHEMSPEC.In this paper,the principles and structure of CHEMSPEC are briefly described,and the strategy and algorithms that were used in this code are interpreted in some detail,such as the measures adopted to prevent divergence in iteratively solving the mass balance equations,the "predictor-corrector" algorithm for calculation of the number and quantities of solid species formed,and the alternate use of "freezing" and "defreezing" oxidation states in handling of co-existent redox and precipitation equilibria.Four examples are given to illustrate CHEMSPEC's features and capabilities.

关键词： chemical speciation modeling code structure algorithms high-level radioactive waste

Discharge simulation and volt-second consumption analysis during ramp-up on the CFETR tokamak

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Chinese Physics B 2020年第2期29卷 356-361页

作者：刘成岳吴斌钱金平李国强侯雅巍韦维陈美霞雷明准郭勇 Physics Department School of Electronic Science&Applied PhysicsHefei University of TechnologyHefei 230601China Institute of Plasma Physics Chinese Academy of ScienceHefei 230026China University of Science and Technology of China Hefei 230031China

The plasma current ramp-up is an important process for tokamak discharge,which directly affects the quality of the plasma and the system resources such as volt-second consumption and plasma current profile.The China Fusion Engineering Test Reactor(CFETR)ramp-up discharge is predicted with the tokamak simulation code(TSC).The main plasma parameters,the plasma configuration evolution and coil current evolution are given out.At the same time,the volt-second consumption during CFETR ramp-up is analyzed for different plasma shaping times and different plasma current ramp rates dIP/dt with/without assisted heating.The results show that the earlier shaping time and the faster plasma current ramp rate with auxiliary heating will enable the volt-second to save 5%-10%.At the same time,the system ability to provide the volt-second is probably 470 V·s.These simulations will give some reference to engineering design for CFETR to some degree.

关键词： plasma current ramp-up China Fusion Engineering Test Reactor tokamak simulation code volt-second consumption

A comparative study of pseudo-static slope stability analysis using different design codes

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Water Science and Engineering 2018年第4期11卷 310-317页

作者： Xin-guang Yang En-di Zhai Yuan Wang Zhong-bo Hu Central Research Institute of Building and Construction Co. Ltd. MCC Group Beijing 100088 China Goldwind Science & Technology Co. Ltd. Beijing 100176 China College of Mechanics and Materials Hohai University Nanjing 210098 China China Three Gorges Corporation Beijing 100038 China

Many researchers have developed new calculation methods to analyze seismic slope stability problems, but the conventional pseudo-static method is still widely used in engineering design due to its simplicity. Based on the Technical code for Building Slope Engineering(GB 50330-2013) of China and the Guidelines for Evaluating and Mitigating Seismic Hazards in California(SP117), a comparative study on the pseudo-static method was performed. The results indicate that the largest difference between these two design codes lies in determination of the seismic equivalence reduction factor( f_(eq)). The GB 50330-2013 code specifies a single value for f_(eq) of 0.25. In SP117, numerous factors,such as magnitude and distance, are considered in determining f_(eq). Two case studies show that the types of slope stability status evaluated by SP117 are in agreement with those evaluated by the seismic time-history stability analysis and Newmark displacement analysis. The factors of safety evaluated by SP117 can be used in practice for safe design. However, the factors of safety evaluated by GB 50330-2013 are risky for slope seismic design.

关键词： Earthquake Slope stability Pseudo-static method Design code

Performance analysis and design of MIMO-OFDM system using concatenated forward error correction codes

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Journal of Central South University 2017年第6期24卷 1322-1343页

作者： Arun Agarwal Saurabh N.Mehta PhD Scholar School of Electrical EngineeringDepartment of Information TechnologyAMET UniversityTamil NaduChennai 603112India Department of Electronics and Telecommunication Engineering Vidyalankar Institute of TechnologyMumbai-400037MaharashtraIndia

This work investigates the performance of various forward error correction codes, by which the MIMO-OFDM system is deployed. To ensure fair investigation, the performance of four modulations, namely, binary phase shift keying(BPSK), quadrature phase shift keying(QPSK), quadrature amplitude modulation(QAM)-16 and QAM-64 with four error correction codes(convolutional code(CC), Reed-Solomon code(RSC)+CC, low density parity check(LDPC)+CC, Turbo+CC) is studied under three channel models(additive white Guassian noise(AWGN), Rayleigh, Rician) and three different antenna configurations(2×2, 2×4, 4×4). The bit error rate(BER) and the peak signal to noise ratio(PSNR) are taken as the measures of performance. The binary data and the color image data are transmitted and the graphs are plotted for various modulations with different channels and error correction codes. Analysis on the performance measures confirm that the Turbo + CC code in 4×4 configurations exhibits better performance.

关键词： bit error rate (BER) convolutional code (CC) forward error correction peak signal to noise ratio (PSNR) Turbo code

Polychronous automata and their use for formal validation of AADL models

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Frontiers of Computer Science 2019年第4期13卷 677-697页

作者： Thierry GAUTIER Clement GUY Alexandre HONORAT Paul LE GUERNIC Jean-Pierre TALPIN Loic BESNARD Univ. Rennes Inria Rennes-Bretagne-Atlantique Research Centre F-35000 Rennes France Univ. Rennes CNRS IRISA F-35000 Rennes France

This paper investigates how state diagrams can be best represented in the polychronous model of computation (MoC) and proposes to use this model for code validation of behavior specifications in architecture analysis & design language (AADL). In this relational MoC, the basic objects are signals, which are related through dataflow equations. Signals are associated with logical clocks, which provide the capability to describe systems in which components obey multiple clock rates. We propose a model of finite-state automata, called polychronous automata, which is based on clock relationships. A specificity of this model is that an automaton is submitted to clock constraints, which allows one to specify a wide range of control-related configurations, being either reactive or restrictive with respect to their control environment. A semantic model is defined for these polychronous automata, which relies on boolean algebra of clocks. Based on a previously defined modeling method for AADL software architectures using the polychronous MoC, the proposed model is used as a formal model for the AADL behavior annex. This is illustrated with a case study involving an adaptive cruise control system.

关键词： architecture modeling formal semantics finitestate automaton polychronous model synchronous concurrency code generation AADL