bluuebunny/crossref_metadata_2025 huggingface dataset:
Research on processing technology of alumina ceramic interlayer composites
Authors: Ren W J , Li X , Shao H F , Hu G X , Shuai L , Cai C , Tuo S, R , Zou S J Y , Chen X D
Published: July 2020

Composite materials which the interlayer is alumina ceramics have the characteristics of high surface toughness, high hardness in the interlayer, high brittleness. To meet the precision of machining process, the quality requirement of the product surface and the requirements of machining processing schedule at the same time, it is difficult to process all kinds of angle and holes. Aiming to solve the difficulties in the processing technology of interlayer composite materials, the choice of machine, knife tools and the processing parameters, as well as the determination of process quality are researched deeply. Meanwhile, the equipment specifications, blade diameter, the relationship between cutting speed and the thickness of interlayer composite materials are all determined. The determination method of process quality is given by the section quality, size precision and the surface quality and other aspects. This paper can guide the processing of related defense composite materials.
Study on differential mode conducted interference of trigger circuit of high-power thyristors in pulsed power supply
Authors: Wei Jiu-fu , Liu Xiang-rong , Luo  , Li Zhen-xiao , Li Bao-ming
Published: July 2020

The trigger circuits of high-power thyristors in pulsed power supply (PPS) contain a large number of pulse transformers, switching MOSFETs (SMFETs) and other passive devices. Fast on-off of SMFETs and pulse transformers often lead to differential mode conducted interference (DMCI) problems in trigger circuits of high-power thyristors. This paper mainly disscusses DMCI problems in trigger circuits of high-power thyristors in the following aspects: initially, circuit models of high-frequency parasitic parameters of pulse transformer and SMFET are established; next, principles of DMCI in trigger circuits of high-power thyristors are investigated; furthermore, DMCI suppression methods are also analyzed; ultimately, experiments have been carried out to verify the theoretical analysis.
Research on a novel integral projectile combining of warhead and armature for the railgun
Authors: Tang B , Xu Y T , Wan G , Jin Y , Li H Y , Li B M
Published: July 2020

Railgun can accelerate the projectile to high speed. The common launching method is using an armature to propel the projectile. When the projectile flies out of the muzzle, armature and sabots are separated from the projectile which become the harmful fragments. Therefore, an integrated projectile which combines the flying warhead and armature is proposed in this paper. This integrated projectile has two advantages, one is that the combination of warhead and armature does not throw dangerous fragments at the muzzle, the projectile has low aerodynamic resistance and flies stability by rotation stability. Another advantage is that in exterior ballistics, the combination of armature increases the total mass of the flying body and may improve the range and damage power. According to the requirements of railgun launching and flight stability of exterior ballistics, structure of the integrated projectile is proposed. Computational fluid dynamics method is used to calculate the aerodynamic characteristics of the new integrated projectile, which is compared with NATO projectile. The calculation shows that the projectile has good aerodynamic characteristics. The rotational stability of the new projectile is calculated and the electromagnetic launch test is carried out. Research of this novel integral projectile will provide reference value for the application of railgun.
Modeling and numerical simulation on launch dynamics of integrated launch package in electromagnetic railgun
Authors: Lin Qinghua , Li Baoming
Published: July 2020

This paper presents a numerical approach to modeling launch dynamics of integrated launch package in railguns. This approach was based on the three-dimensional transient finite element solutions of the multi-physical field equations. Numerical simulations were conducted for a railgun system composed of the capacitor-based pulse forming network, advanced containment launcher, and integrated launch package. Some issues about induced eddy currents, stress distributions, and projectile lateral motions were discussed. The results show that the in-bore motion of the projectile is sensitive to the launch package configuration and launcher stiffness. Moreover, the armature under a heavy current is prone to serious deformation and then leads to launch failure. The launch dynamics model provides a method to predict the in-bore processes and evaluate the in-bore survivability of the integrated launch package in a railgun.
Firing range optimization of a 155mm uni-modular charge howitzer by ETC technology
Authors: Jin Yong , Ni Yanjie , Zhao Liangyou , Cheng Niankai , Wan Gang , Li Baoming
Published: July 2020

Electrothermal-chemical (ETC) launch technology can accurately control and enhance the ignition and combustion of solid propellants to improve the consistency and accuracy of ballistics. In this paper, a calculation model including the transient burning rate formula and six-degree-of-freedom rigid body trajectory equation is established to simulate both interior and exterior ballistics processes for a 155mm uni-modular charge howitzer. The simulation results show that the muzzle velocities are optimized via the ETC technology. The 155mm uni-modular charge ETC howitzer can effectively obtain the minimum range, increase the range overlap and maximum range, and improve the ballistic stability and consistency.
An initial velocity model study of electromagnetic railgun based on back propagation neural network
Authors: Liu J G , Dong Z Q , Ren R , Sh Ye W , Zhang C H , Li J H
Published: July 2020

The velocity of launch has been the key factor restricting the application of electromagnetic rail. For electromagnetic launch system, the structural parameters change directly or indirectly affect the Launching velocity of the electromagnetic launch system. In order to improve the initial velocity of the electromagnetic railgun. The mathematical model of electromagnetic rail gun launch was set up, the structure parameters of armature and the size of the pretension force between armature and orbital were variables, based on the target function, The equivalent model of rail gun BP neural network is established by using the calculation results of mathematical model, and the model of rail gun BP neural network was optimized by electromagnetic emission test data. The error of rail gun BP neural network model optimized by experimental data is 18.5% lower than that before optimization and 6.5% lower than that of experimental data. The results show that the launch speed of the optimized rail gun BP neural network model is closer to the actual speed.
Model updating of gun recoil mechanism based on time domain response
Authors: Liu J , Xu H Y , Zhou C J , L Y , Liu P K , He Q
Published: July 2020

For gun launching dynamics modeling, the accuracy of the recoil and counterrecoil model is important. In order to improve the accuracy of gun recoil mechanism modeling, the rigid-flexible coupling firing dynamics model of a small-caliber gun was established, and the recoil displacement of the gun was tested by live firing test. Aiming at the error between the simulation curve and the test curve of the recoil displacement changing with time, taking the correlation coefficient of the two curves as the objective function, the dynamics model of the recoil mechanism was modified based on the time-domain response using the optimization algorithm. The modified results show that the difference of the maximum recoil displacement decreases from 9% to 0.1%, and the similarity between the simulation curve and the test curve reaches 0.99. The modified results based on the time-domain response effectively improve the accuracy of the recoil model, so that the established dynamics model can more truly reflect the dynamic characteristics of the recoil mechanisms, and provide the basic conditions for ensuring the simulation accuracy of the launch dynamics model.
A study on finite element model updating method for recovery airbag
Authors: Li J Y , Song S P
Published: July 2020

It needs FE(finite element) model updating of recovery airbag for improving simulation accuracy of cushion process. In this paper, the FE model was updated based on drop tests of payload-airbags system. Firstly, FE model of payload-airbags was established. Two parameters, include discharge coefficient of vent and friction coefficient between airbag and ground, were selected for updating by sensitivity analysis. The response surfaces of impact response vs the two parameters were established based on Design of experiments and FE model. Based on the response surfaces, the optimal solutions were solved by Genetic algorithm. It indicated that the FE model updating of airdrop airbag was efficient through comparison of test results and simulate results before and after updating.
Damage evolution around shear loaded inter-void ligaments
Authors: Chen S , Osovski S
Published: July 2020

The dimpled fracture surfaces observed in a post-mortem investigation of the ductile fracture indicates that the fracture formed through coalescing voids that originated at the microstructural level. The damage process is commonly described by the nucleation and growth of those voids, thinning the inter-void material ligaments, ultimately leading to final fracture. The final stages of the ductile fracture process will be discussed, with emphasis on the local plastic deformation field in the void’s surroundings. This study considers dominant shear loading as the driving force for plastic deformation, using periodic cell calculations and the GTN model modified for shear damage. We systematically investigate plane strain and plane stress configurations, as a realization of the ligament thinning as part of the ductile fracture process. We suggest that the void surroundings and the intervoid ductile ligament undergoes an idealized gradual transition from plane strain to plane stress as the ligament gets increasingly thinner. While the present study addresses quasi-static failure, it is believed that the framework presented here can be extended to dynamic loading situations as well.
Fin stabilized projectiles point mass model
Authors: Meda Tomasz
Published: July 2020

To calculate flight of unguided projectiles several types of the flight models are used. The application mostly depends on demand of the model accuracy, complexity and computational cost. As a good compromise of these three features for flight calculation of spin stabilized projectiles Modified Point Mass Trajectory Model was created. The MPMTM is commonly used for firing tables creation. In the paper the author shown conception of flight model designed for fin (aerodynamic) stabilized projectiles. At In the first part of the paper the motivation of the model designing was explained. Additionally analysis of the phenomena that should be used in the model was made. In the next part of the paper main equations of the model were described. Some of them were empirical. In the third part of the paper the accuracy of the designed model and two other model types was compared. Calculations results were compared with experimental data and the conclusion were drawn.
Investigation on properties of FeNi intermetallics under pressure by First-principles
Authors: Wang M J , Zhang G W , Xu H
Published: July 2020

In this paper, the structural stabilities, elastic, electronic and magnetic properties of three binary Fe-Ni intermetallics with different structure under pressure have been systematically investigated by first-principle method based on density functional theory. The results indicated that the lattice parameters and bulk modulus of Fe-Ni compounds at zero pressure match well with other experimental data and available theoretical calculated values. The calculated energy-volume and pressure-volume expressed that all the compounds are mechanical stability under pressure, and the volume variation increase with the increasing iron content under pressure. The shear deformation resistant and volume deformation resistant are estimated by elastic constant Cij and bulk modulus B. Meanwhile, applied pressure improved the ductility of the Fe-Ni compounds, elastic anisotropy of three compounds under pressure are arranged in the following order: Fe3Ni>FeNi>FeNi3. Debye temperature ΘD of compounds gradually increase with the increase of iron contents and pressure, the temperature dependence of the linear thermal expansion coefficient α and heat capacity (CV and CP) are also calculated based on quasi-harmonic Debye model under pressure from 0 to 50GPa and various temperature. The results gain a better understanding of iron-nickel alloys.
Study of the influence of electrical parameters on launch performance of projectile from the single-stage reluctance coil launcher
Authors: Li Zh Y , Shen Y L , Li H R , Song L N
Published: July 2020

To increase the exit velocity of projectile from single-stage reluctance coil launcher, the theoretical analysis is conducted for the projectile acceleration principle. The influence law of the electrical parameters on the projectile velocity is obtained, by the imitation research about the influence rule of the variation of electrical parameters (including capacitor voltage and capacitance) in a single-stage reluctance coil emitter on the transmitting performance, using the two-dimensional transient field solver in the finite element analysis software of Ansoft. At the same time, the single-stage reluctance coil launcher is also set up to conduct relevant tests, and the correctness of simulation analysis is verified. The results show that increasing the voltage and capacitance of the capacitor is beneficial to increase the exit velocity of the projectile, in the condition that the relative position of the projectile and driving coil is constant, The capacitor voltage is less than 1000V, and the capacitor capacitance is less than 1500μF. The simulation and experiment results provide guidance for the related analysis and study of multi-stage reluctance coil launcher.
Research on optimize application of Buckingham Pi theorem to wind tunnel test and its aerodynamic simulation verification
Authors: Hu Pengfei , Chang Chia-kan
Published: July 2020

In physical modeling, especially in the field of wind tunnel tests, dimensional analysis is essential, but the existing dimensional analysis methods are difficult to select the appropriate physical quantities. Therefore, based on the improvement of existing dimensional analysis methods for wind tunnel tests, a set of optimized dimensional analysis methods for wind tunnel tests based on Buckingham Pi theorem was derived in this paper, and then we put forward an aerodynamic simulation experiment based on fluent to verify this method.
Simulation analysis on explosion safety of intense light stun grenades
Authors: Ma Y Zh , Yang D Ch
Published: July 2020

To evaluate the explosion safety of intense light stun grenades, an explosion simulation model was established for their explosion bodies based on a LS-DYNA simulation platform. In this way, both the distribution rules and velocity variations of fragments can be analyzed. As indicated by the simulation results, their fragments are proven to be non-uniformly distributed as far as their sizes are concerned; and, low-velocity fragments with a large mass produced in the middle of the explosion body are the major sources of damage. Moreover, the corresponding radius of safety turns out to be 2.33m approximately. In a word, such an investigation provides a scientific basis for the R&D and applications of intense light stun grenades.
Three loop QCD corrections to heavy quark form factors
Authors: Ablinger J. , Blümlein J. , Marquard P. , Rana N. , Schneider C.
Published: July 2020

Higher order calculations in perturbative Quantum Field Theories often produce coupled linear systems of differential equations which factorize to first order. Here we present an algorithm to solve such systems in terms of iterated integrals over an alphabet the structure of which is implied by the coefficient matrix of the given system. We apply this method to calculate the master integrals in the color–planar and complete light quark contributions to the three-loop massive form factors.
CutLang: a cut-based HEP analysis description language and runtime interpreter
Authors: Unel G. , Sekmen S. , Toon A.M.
Published: July 2020

We present CutLang, an analysis description language and runtime interpreter for high energy collider physics data analyses. An analysis description language is a declerative domain specific language that can express all elements of a data analysis in an easy and unambiguous way. A full-fledged human readable analysis description language, incorporating logical and mathematical expressions, would eliminate many programming difficulties and errors, consequently allowing the scientist to focus on the goal, but not on the tool. In this paper, we discuss the guiding principles and scope of the CutLang language, implementation of the CutLang runtime interpreter and the CutLang framework, and demonstrate an example of top pair reconstruction.
The Controls and Configuration Software of the Atlas Data Acquisition System for LHC Run 2
Authors: Kazarov A , Aleksandrov I , Avolio G , Caprini M , Chitan A , Corso Radu A , Kazymov A , Lehmann Miotto G , Mineev M , Santos A , Soloviev I , Vasile M , Unel G
Published: July 2020

The ATLAS experiment at the Large Hadron Collider (LHC) operated very successfully in the years 2008 to 2013, a period identified as Run 1. ATLAS achieved an overall data-taking efficiency of 94%, largely constrained by the irreducible dead-time introduced to accommodate the limitations of the detector read-out electronics. Out of the 6% dead-time only about 15% could be attributed to the central trigger and DAQ system, and out of these, a negligible fraction was due to the Control and Configuration sub-system. Despite these achievements, and in order to improve the efficiency of the whole DAQ system in Run 2 (2015-2018), the first long LHC shutdown (2013-2014) was used to carry out a complete revision of the control and configuration software. The goals were three-fold: properly accommodate additional requirements that could not be seamlessly included during steady operation of the system; re-factor software that had been repeatedly modified to include new features, thus becoming less maintainable; and seize the opportunity of modernizing software written even before Run 1, thus profiting from the rapid evolution in IT technologies. This upgrade was carried out retaining the important constraint of minimally impacting the mode of operation of the system and public APIs, in order to maximize the acceptance of the changes by the large user community. This paper presents, using a few selected examples, how the work was approached and which new technologies were introduced into the ATLAS DAQ system, and how they were performing in course of Run 2. Despite these being specific to this system, many solutions can be considered and adapted to different distributed DAQ systems.
Heterogeneous computing for the local reconstruction algorithms of the CMS calorimeters
Authors: Massironi Andrea , Khristenko Viktor , DAlfonso Mariarosaria
Published: July 2020

The increasing LHC luminosity in Run III and, consequently, the increased number of simultaneous proton-proton collisions (pile-up) pose significant challenges for the CMS experiment. These challenges will affect not only the data taking conditions, but also the data processing environment of CMS, which requires an improvement in the online triggering system to match the required detector performance. In order to mitigate the increasing collision rates and complexity of a single event, various approaches are being investigated. Heterogenous computing resources, recently becoming prominent and abundant, may be significantly better performing for certain types of workflows. In this work, we investigate implementations of common algorithms targeting heterogenous platforms, such as GPUs and FPGAs. The local reconstruction algorithms of the CMS calorimeters, given their granularity and intrinsic parallelizability, are among the first candidates considered for implementation in such heterogenous platforms. We will present the current development status and preliminary performance results. Challenges and various obstacles related to each platform, together with the integration into CMS experiments framework, will be further discussed.
Automated and Intelligent Data Migration Strategy in High Energy Physical Storage Systems
Authors: Cheng Zhenjing , Wang Lu , Cheng Yaodong , Chen Gang
Published: July 2020

As a data-intensive computing application, high-energy physics requires storage and computing for large amounts of data at the PB level. IHEP computing center is beginning to use tiered storage architectures, such as tape, disk or solid state drives to reduce hardware purchase costs and power consumption. At present, automatic data migration strategies are mainly used to resolve data migration between memory and disk. So the rules are relatively simple. This paper attempted to use the deep learning algorithm model to predict the evolution trend of data access heat as the basis for data migration. The implementation of some initial parts of the system were discussed, as well as the file trace collector and the LSTM model. At last some preliminary experiments are conducted with these parts.
In-Memory Parallel Computing for Partial Wave Analysis
Authors: Wei Zhanchen , Huang Qiulan , Sun Gongxing , Liu Xiaoyu
Published: July 2020

The traditional partial wave analysis (PWA) algorithm is designed to process data serially which requires a large amount of memory that may exceed the memory capacity of one single node to store runtime data. It is quite necessary to parallelize this algorithm in a distributed data computing framework to improve its performance. Within an existing production-level Hadoop cluster, we implement PWA algorithm on top of Spark to process data storing on low-level storage system HDFS. But in this case, sharing data through HDFS or internal data communication mechanism of Spark is extremely inefficient. In order to solve this problem, this paper presents an in-memory parallel computing method for PWA algorithm. With this system, we can easily share runtime data in parallel algorithms. We can ensure complete data locality to keep compatibility with the traditional data input/output way and cache most repeatedly used data in memory to improve the performance, owe to the data management mechanism of Alluxio.
Real-time cluster finding for LHCb silicon pixel VELO detector using FPGA
Authors: Lazzari Federico , Bassi Giovanni , Cenci Riccardo , Morello Michael J , Punzi Giovanni
Published: July 2020

In the Run-3 of LHCb, the High Level Trigger will have to process events at full LHC collision rate (30 MHz). This is a very challenging goal, and delegating some low-level tasks to FPGA accelerators can be very helpful by saving precious computing time. In particular, the 2D pixel geometry of the new LHCb VELO detector makes the cluster-finding process particularly CPU-time demanding. We realized and tested a highly parallel FPGA-based clustering algorithm, capable of performing this reconstruction in real time at 30 MHz event rate using a modest amount of hardware resources, that can be a viable alternative solution.
Speeding HEP Analysis with ROOT Bulk I/O
Authors: Bockelman B , Zhang Z , Shadura O
Published: July 2020

Distinct HEP workflows have distinct I/O needs; while ROOT I/O excels at serializing complex C++ objects common to reconstruction, analysis workflows typically have simpler objects and can sustain higher event rates. To meet these workflows, we have developed a “bulk I/O” interface, allowing multiple events’ data to be returned per library call. This reduces ROOT-related overheads and increases event rates – orders-of-magnitude improvements are shown in microbenchmarks.

Unfortunately, this bulk interface is difficult to use as it requires users to identify when it is applicable and they still “think” in terms of events, not arrays of data. We have integrated the bulk I/O interface into the new RDataFrame analysis framework inside ROOT. As RDataFrame’s interface can provide improved type information, the framework itself can determine what data is readable via the bulk IO and automatically switch between interfaces. We demonstrate how this can improve event rates when reading analysis data formats, such as CMS’s NanoAOD.
Towards a coherent Data Life Cycle in Astroparticle Physics
Authors: Tokareva V , Haungs A , Kang D , Kostunin D , Polgart F , Wochele D , Wochele J
Published: July 2020

The German-Russian Astroparticle Data Life Cycle Initiative (GRADLCI) aims to develop a data life cycle (DLC), namely a clearly defined and maximally automated data processing pipeline for a combined analysis of data from the experiment KASCADE-Grande (Karlsruhe, Germany) and experiments installed at the Tunka Valley in Russia (TAIGA). The important features of such an astroparticle DLC include scalability for handling large amounts of data, heterogeneous data integration, and exploiting parallel and distributed computing at every possible stage of the data processing. In this work we provide an overview of the technical challenges and solutions worked out so far by the GRADLCI group in the framework of a far-reaching analysis and data center. We will touch the peculiarities of data management in astroparticle physics and employing distributed computing for simulations and physics analyses in this field.
Explore cloud solutions for ATLAS with $250,000 AWS cloud credits
Authors: Bawa H. , Gao Y. , Moss J. , Grimm K.
Published: July 2020

Maintaining the huge grid computing facilities for LHC experiments and replacing their hardware every few years has been very expensive. The California State University (CSU) ATLAS group recently received $250,000 AWS cloud credit from the CSU Chancellor’s Office to build the first virtual US ATLAS Tier 3 to explore cloud solutions for ATLAS. We will use this award to set up full ATLAS computing environments on the cloud for ATLAS physics analysis frame works, MC generation, simulation and production. We will also develop policies for ATLAS members to submit jobs to the cloud and develop an economic model focused especially on the cost effectiveness of cloud solutions for ATLAS through extensive real user experience. The results will help ATLAS computing and physics communities decide future directions with incoming LHC upgrades.
Incorporation of systematic uncertainties in the training of multivariate methods
Authors: Alef Thomas , Toerne Eckhard von
Published: July 2020

Due to the large size of datasets accumulated at the LHC, analysis results are often limited by systematic effects. The application of multivariate analysis techniques such as Boosted Decision Trees (BDTs) or artificial neural nets typically maximises the statistical significance of the results while ignoring systematic effects. There is a known strategy to mitigate systematic effects for neural nets but no firmly established procedure for BDTs. We present a method to incorporate systematic uncertainties into a BDT, the systematics-aware BDT (saBDT). We evaluate our method on open data of the ATLAS Higgs machine learning challenge and compare our results to neural nets trained with an adversary.
Machine Learning on sWeighted data
Authors: Borisyak M , Kazeev N
Published: July 2020

Data analysis in high energy physics has to deal with data samples produced from different sources. One of the most widely used ways to unfold their contributions is the sPlot technique. It uses the results of a maximum likelihood fit to assign weights to events. Some weights produced by sPlot are by design negative. Negative weights make it difficult to apply machine learning methods. The loss function becomes unbounded. This leads to divergent neural network training. In this paper we propose a mathematically rigorous way to transform the weights obtained by sPlot into class probabilities conditioned on observables, thus enabling to apply any machine learning algorithm out-of-the-box.
Automated performance tuning of distributed storage system based on deep reinforcement learning
Authors: Wang Lu , Zhang Wentao , Cheng Yaodong
Published: July 2020

Automated performance tuning is a tricky task for a large scale storage system. Traditional methods highly reply on experience of system administrators and cannot adapt to changes of working load and system configurations. Reinforcement learning is a promising machine learning paradigm which learns an optimized strategy from the trials and errors between agents and environments. Combining with the strong feature learning capability of deep learning, deep reinforcement learning has showed its success in many fields. We implemented a performance parameter tuning engine based on deep reinforcement learning for Lustre file system, a distributed file system widely used in HEP data centres. Three reinforcement learning algorithms: Deep Q-learning, A2C, and PPO are enabled in the tuning engine. Experiments show that, in a small test bed, with IOzone workload, this method can increase the random read throughput by about 30% compared to default settings of Lustre. In the future, it is possible to apply this method to other parameter tuning use cases of data centre operations.
Deep Learning applied to hit classification for the BESIII drift chamber
Authors: Zhang Yao , Yuan Ye , Ma Qiumei
Published: July 2020

Drift chamber is the main tracking detector for high energy physics experiment BESIII. Due to the high luminosity and high beam intensity, the BESIII drift chamber is suffered from the beam background and electronics noise which represent a computing challenge to the reconstruction software. Deep learning developments in the last few years have shown tremendous improvements in the analysis of data especially for object classification. Here we present a first study of deep learning architectures applied to the real data of BESIII drift chamber to accomplish the hit classification of the background and signal.
Electromagnetic shower generation with Graph Neural Networks
Authors: Belavin V. , Ustyuzhanin A.
Published: July 2020

In this work, we propose an approach for electromagnetic shower generation on a track level. Currently, Monte Carlo simulation occupies 50-70% of total computing resources that are used by physicists experiments worldwide. Thus, speedup of the simulation step allows to reduce simulation cost and accelerate synthetic experiments. In this paper, we suggest dividing the problem of shower generation into two separate issues: graph generation and tracks features generation. Both these problems can be efficiently solved with a cascade of deep autoregressive generative network and graph convolution network. The novelty of the proposed approach lies in the application of graph neural networks to the generation of a complex recursive physical process.
Generalization of Homogeneity Tests for Weighted Samples and Their Implementation in ROOT
Authors: Trusina Jakub , Franc Jiří , Novotný Adam
Published: July 2020

In High Energy Physics, tests of homogeneity are used primarily in two cases: for verification that data sample does not differ significantly from numerically produced Monte Carlo sample and for verifying separation of signal from background. Since Monte Carlo samples are usually weighted, it is necessary to modify classical homogeneity tests in order to apply them to weighted samples. In ROOT, the only homogeneity tests that allow testing weighted samples are implemented for binned data. However, after the data are binned the full information is lost. Therefore we compare these ordinary tests with modified versions of the Kolmogorov-Smirnov, Anderson-Darling, and Cramér-von Mises tests that use full sample information. The proposed tests are compared by estimating a probability of type-I error which is crucial for a test’s reliability.
Impact of climate change on rainfall over Chennai
Authors: Athira T , Agilan V
Published: July 2020

Global warming and climate change are currently topics of importance in environmental studies. Climate change is predominantly contributed by human activities and it presents a serious threat to nature and people. Greenhouse gasses such as carbon dioxide trap heat in the atmosphere and regulate climate. In addition, rapid urbanization and industrialization add more greenhouse gases to atmosphere and increase overall global temperature and further change the weather patterns. The unexpected weather conditions in Chennai has gained wide attention, especially after 2015 flood, Vardah and Ocki cyclones. In this study, the possible impact of climate change on rainfall over Chennai city is analysed under various Representative Concentration Pathway (RCP) scenarios. Simulations of a Coordinated Regional Climate Downscaling Experiment (CORDEX) Regional Climate Model (RCM) is downscaled using change factor method. The study results show that the intensity and frequency of extreme rainfall over Chennai is likely to increase.
Analytical evidence for deep ocean warming trend in tropical Indian Ocean
Authors: Malavika A R , Pai Maya L , Saji P K
Published: July 2020

The present climate change has a warming impact on the Earth’s climate system, hence called as global warming. Study about oceans is relevant to the current scenario of changing climate and many studies show significant warming trends in the Sea Surface Temperature (SST) in the ocean during the past several decades. Extensive warming is found in deeper layers of oceans too. In this study, the monthly mean deep ocean temperature data which was spatially averaged over the tropical Indian Ocean (IO) during the period 1950 to 2012 was subjected to a statistical EMD analysis to estimate the impact of warming to deeper IO. The temperature signal is decomposed into components called as Intrinsic Mode Functions (IMFs) along with a residual part. The IMFs represent the temperature fluctuations resulting from inter-annual oscillations such as ENSO (El-Nino Southern Oscillation) and the residual part can be considered as the long-term trend. The IMFs obtained at each depth showed variabilities in QBO, ENSO and tidal frequencies. Residual part of the signal too had significant magnitudes, indicating the impact of global warming signals at deeper oceans.
Trace metal partitioning in a shallow estuary, Muthupet, India
Authors: Priya K L , Haddout S
Published: July 2020

Dissolved trace metal concentrations of Fe, Cd, Cu and Zn were analysed in the Muthupet estuary, a well-mixed micro-tidal estuary in India during the post-monsoon and pre-monsoon in 2014. There was a significant variation in the salinity and suspended sediment concentration over the seasonal scale with peak salinity occurring at the downstream mouth during the post-monsoon and at intermediate locations during the pre-monsoon. Strong seasonal variations were observed in the concentration of trace metals. The concentration of Fe, Cd and Zn exceeded the USEPA standards, while that of Cu was within the permissible limits. Fe, Cu and Zn showed non-conservative behavior with peak concentrations at mid-estuarine reaches, irrespective of the location of salinity maxima, while the peak concentration of Cd occurred at high salinity reaches. The complexation of Cd as chlorocomplexes enhanced the mobilization of Cd, resulting in a peak value at high salinity reaches. The study indicated that the estuary is influenced by oceanic water and the anthropogenic input is secondary. Resuspension of bed sediments is identified as the major process controlling the trace metal concentration. Partition coefficient (Kd) of Fe, Cu and Zn was observed to be an increasing function of salinity, of which, the effect on Fe was much significant. The coagulation of suspended sediments at high salinity reaches enhanced the removal of Fe as Fe oxyhydroxides.
Investigations on the flexural performance of laminated glass
Authors: Ravimony Raji , Joseph Anitha , Mangal Lalu
Published: July 2020

Laminated Glass, regarded as the safety glass, is widely used in modern architectural applications. The structural behaviour of this type of glass is highly complex owing to the presence of the interlayer. In such a case, classical theoretical formulations are of no use and it becomes necessary to employ specially formulated equations or numerical simulations to evaluate the performance of laminated glass. Present work consists of displacement-controlled four-point bending tests on laminated glass beams to study the load-deflection behaviour and fracture pattern of the samples. Numerical simulations of the test samples are carried out in ANSYS to achieve the maximum tensile stress and deflection values corresponding to the initial failure load. Three laminated glass performance models are used to analytically evaluate the values of failure stress for laminated glass.
Study on behaviour of cast steel K-joints in circular hollow sections
Authors: Biju V , Bindhu K R , Mangal Lalu
Published: July 2020

Circular hollow sections are commonly used in steel industry and many types of joints like T, K, X etc., are encountered during the construction phase. The joints can be connected using weld or bolt assembly. In this paper, an attempt is made to study the response of K joints using cast steel nodes when subjected to quasi-static cyclic loading. Eight specimens are fabricated and connected using steel nodes to form K-joints and are tested under quasi-static cyclic loading. From the experimental study, ultimate failure load under tension and compression, mode of failure, hysteresis curve and load deflection envelope are determined. The load values obtained are compared with design strength values of welded K-joint and longitudinal gusset plate connected T-joint specimens as predicted by AISC and CIDECT guidelines. The study reveals that cast steel nodes can be used as an alternative for connecting joints and the strength obtained is slightly higher than that predicted with longitudinal gusset plate connected T-jointed specimens.
Experimental and analytical studies on the compression properties of scrap tyre pad base isolators
Authors: Mathew Ancy , Firdouse F S , Sajeeb R
Published: July 2020

Base isolation is one of the widely accepted seismic protection strategy. Scrap tyre pads have been identified to be suitable for the design of low-cost base isolation systems. The present study attempts to group scrap tyres of different brands based on their physical parameters and material properties. Five types of scrap tyres, from the same size group, have been identified in the present study. Tensile strength characteristics of scrap tyre pads were assessed by conducting experiments using ASTM D 638 specifications. The study investigates the compressive behaviour of seismic isolators made from different types of scrap tyre pads. Vertical stiffness and load bearing capacity of scrap tyre pad isolators were assessed for all the five types of scrap tyre pads. Three-dimensional finite element models of isolators were also developed and the response was found to be matching reasonably well with the experimentally observed response.
Key performance indicators of sustainability
Authors: Nair Aparna , Nayar Seema K
Published: July 2020

Sustainable construction involves the judicious use of resources so as to satisfy the demands of both present and future generations. It is supported on three pillars namely economic, environmental and social. This study aims to understand the key performance indicators of sustainability. Based on the literature review, this study develops a set of performance indicators relevant to Indian construction industry. Questionnaires and interviews are conducted among the architects and engineers. Using Relative Importance Index, the identified indicators are prioritised.
Analysis of factors influencing mode shift to public transit in a developing country
Authors: Devika R , Harikrishna M
Published: July 2020

Vehicles are a major invention having significant impact on human progress.However, increasing private vehicle usage can cause many threats to the society like congestion, depleting environmental quality etc. The study is taken up to identify the factors influencing usage of private and public modes, with the help of mode choice models. The influence of psychological factors based on the ‘Theory of Planned Behaviour’ were analysed in the study.The variables considered for the study include service attributes like travel cost, travel time, waiting time, comfort and latent variables like ‘attitude’, ‘subjective norm’, ‘perceived behavioural control’ etc. Revealed preference survey was adopted to know the sociodemographic details and a stated preference survey was adopted to study the mode shift of people to a better public transit facility.Travel time, waiting time and travel cost had negative influence in the utility of new public transit mode.Comfort and perceived behavioural control had positive influence in utility of a new public transit service.The study was useful in developing a better understanding of mode choice behaviour and developing insights for policy formulations for improving the public transit.
Mechanism of Condensation Enhancement by Corrugated Low Finned Tubes in Presence of Noncondensable Gas
Authors: Ren Bin , Pu Zhe , Tang Xiaoying , Wang Jifeng , He Aini , Lu Hongliang
Published: July 2020

Corrugated tubes are the most convenient reinforcement techniques to enhance intube condensation. In this paper, the average condensation heat transfer coefficients inside the corrugated low finned tube and smooth tube were firstly introduced. The distribution of local heat transfer coefficient was presented at lower and higher inlet noncondensable gas mass fractions. The results show that the major heat transfer resistance is the thermal resistance of liquid film at lower inlet gas fraction. So the mechanism of condensation enhancement by corrugated low finned tubes is the increase of liquid film condensation coefficient. But at higher inlet gas fraction gas layer mass transfer resistance becomes the control thermal resistance. The spiral ribs inside corrugated low finned tube can thinner not only the gas layer thickness but also the liquid film thickness. The mechanism of condensation enhancement is the increase of both gas layer and liquid film condensation coefficient.
Knowledge Capital Management Mechanism of Smart Library Ecosystem
Authors: Shu Zongying , Jiang Yiqun , Huang Jiangshan , Wang Maohan , Liu Jia
Published: July 2020

The development of smart libraries makes users more and more personalized in their knowledge needs, study the intelligent library knowledge ecosystem, and conduct in-depth research on their knowledge capital management mechanism, which can achieve innovation in library services. This article first combs the concept of smart library knowledge capital, and then analyzes the smart library knowledge ecosystem in detail, and discusses the operation mode of smart library knowledge capital. The knowledge ecosystem has enhanced the dynamics and openness of knowledge information in smart libraries through the sharing and innovation of knowledge capital.
Melting-assisted Synthesis of Hierarchical SSZ-13 Zeolite
Authors: Wang Guangjian , Li Fangni , Li Qiang , Bing Liancheng
Published: July 2020

In order to reduce the diffusion resistance of the reactants and products in the traditional microporous SSZ-13 zeolite, a hierarchical SSZ-13 zeolite was synthesized with melting-assisted method. The hierarchical SSZ-13 zeolite was easily and quickly synthesized by ammonium fluoride solid-phase grinding under solvent-free condition. The obtained SSZ- 13 samples were characterized by XRD, SEM, BET and EDS. The results clearly indicate that the etched zeolite contains micropores and mesopores, and in addition, no significant decrease of crystallinity is observed for the sample etched with ammonium fluoride. Using this method, other zeolites with CHA, MFI, and TON topologies were etched successfully.
Evaluation of Ecological Vulnerability of County Areas in Karst Mountain Area Based on VSD Model-A Case Study of Duyun City
Authors: Zhou Yuyang , Zhou Guofu , Huang Qifen , Yue Li
Published: July 2020

This thesis can provide a more reasonable and accurate basis for county environmental management in karst regions, by evaluating the ecological vulnerability of Duyun area. The VSD model (Vulnerability Scoping Diagram) was used to construct a comprehensive evaluation of 29 indicators, including natural and human factors through exposure, sensitivity, and adaptability. The results showed that: According to the effects of ecological vulnerability, the environmental vulnerability of Duyun City is mainly mild.The slightly vulnerable area, the mildly vulnerable area, the moderately vulnerable area, the highly vulnerable area and the extremely vulnerable area account for 17.95%, 30.78%, 21.18%, 24.17% and 5.92%. The environmental environment of Duyun City is mainly mildly vulnerable, and the ecological situation in some areas is very delicate. High vulnerable areas and extreme vulnerable areas should actively carry out ecological protection construction, rationally urban layout development, and industrial building.Towns that are located in mildly and moderately vulnerable areas should rely on their abundant natural environment resources and location advantages to conduct moderate development, promote rural revitalization and development, and build ecologically livable cities.
Study on Stability and Reliability of Cement-Sand-Gravel Dam
Authors: Li Xiuwen , Zhang Shunfu , Wu Hao , Tian Dongcheng
Published: July 2020

The cement-sand-gravel (CSG) dam is a new type of dam between the rockfill dam and the gravity dam, with advantages of both these two types of dams. The materials used to build the CSG dams have low shear strength and large dispersion. To study the stability and reliability of equal-height gravity dams and SCG dams, finite element software was used to conduct static analysis on the 100 m gravity dams and SCG dams, and the JC method was used to compute the reliability of dams based on the analysis result. The research results show that under the same working conditions, the CSG dam has better reliability and better adaptability to the foundation than the gravity dam. The study is expected to provide a basis for the design and application of CSG dams.
Analysis of the dynamic characteristics of salinity intrusion in Shiziyang
Authors: Yuan Fei , Lu Chen , Yang Yugui
Published: July 2020

This paper studies the law of the salt water intrusion of Shiziyang based on the salinity measurement data in the dry season of Shiziyang, and we can summarize the following characteristics: the salty fresh water in the upstream of Shiziyang is fully mixed, the downstream saltwater belongs to the partial mixed, saltwater is layered obviously during the neap tide, and the mixing effect is the best during the moderate tide. During the neap tide, downstream salt water is layered significantly, and hyperhaline invades rapidly from the bottom, fresh water discharges from the surface; during the moderate tide, salt fresh water mixes well, the salt boundary is the farthest from the estuary at the minimum flood moment; after the spring tide, salt water mixing gradually weakens, forming a salt water wedge.
Ocean erosion: the main cause of Zhangjiajie landform
Authors: Li Yaohuang
Published: July 2020

The available evidence indicates that ocean erosion is the main cause of Zhangjiajie landform. It is the strength of the sea that has created Zhangjiajie's unparalleled magnificent scenery. The various micro-landforms in Zhangjiajie landforms respectively correspond to various ancient sea-eclipse micro-landforms, such as ancient sea erosion headland bay, ancient sea erosion cliff, ancient sea erosion arch bridge, ancient sea erosion column, ancient sea erosion platform, ancient sea erosion cave and so on.