一种基于动态拓扑的流计算性能优化方法及其在Storm中的实现

响应性和稳定性一直是流式计算中两个至关重要的问题,而流计算系统在过载时常常表现出数据计算延迟增加和拓扑不稳定的现象,无法适应数据负载的动态变化.针对这一问题本文研究提出了一种基于动态拓扑的流计算性能优化方法,主要包括:(1)动态逐级反压:拓扑中的任务可以根据当前自身负载情况,动态调整上游向其发送数据的速率.(2)无状态拓扑数据重放:拓扑不维持数据的计算状态,尽可能地实现数据容错.(3)自适应拓扑替换:在拓扑不暂停的情况下对任务并发度进行自发调整.(4)延迟持久化队列:拓扑中对磁盘的IO读写被延迟到数据处理之外,减缓IO高频阻塞对流计算系统的影响.本文在Apache Storm中实现了以上四种方案,性能测试结果表明优化后的流计算系统与Storm默认实现相比,不仅增强了大数据动态匹配能力,而且在最优情况下改善了17%的吞吐量,并提升了约20%的数据处理速度.

计算机客货流图处理系统的研究

客货流图是铁路运输、计划和客运等核心部门使用的重要的实际资料。阐述了计算机客货流图处理系统的设计。

NUMERICAL SIMULATION ON AERODYNAMIC CHARACTERISTICS OF WINDBLAST PROTECTION AT HIGH SPEED

The computational fluid dynamics （CFD） method is used to investigate the aerodynamic characteristics of the seat/occupant with windblast protection devices. The upwind Osher scheme is used for the spatial discretisation. The detached-eddy simulation （DES） based on the Spalart-Allmaras one-equation turbulence model is ap- plied to the detached viscous flow simulation behind the seat/occupant, with Mach numbers 0.6 and 1.2 at attack angles between --10 and 30°, and at two sideslip angles of 0 and 15°, respectively. The aerodynamic characteristics of seat/occupants with and without windblast protection devices are calculated in cases of the freestream Mach numbers 0. 8 and 1.6, attack angles from 5 to 30°, and three sideslip angles of 0, --20 and --50°, respectively. Results show that simulation results agree well with experimental data. And the occupant is efficiently protected by windblast protection devices.

Simulation study on combustion system of tankless gas water heater

This paper simulates the combustion system of a regular tankless gas water heater under different static pressure conditions.The simulation results are in accordance with the test results.It proves that the used physical and mathematical models are reasonable.The results show that the flame height and the excess air ratios depend on the system pressure drop but not on the absolute pressure at the combustion chamber.The pressure drop and the amount of combustion air have an inverse relationship with CO generation,and they also impact on the temperature and velocity fields.To reduce CO emission,a stronger fan is needed to provide extra pressure head to ensure that enough combustion air is introduced into the system.This study provides a useful research tool to develop products through computational fluid dynamic analysis and laboratory testing.

The Contribution of Opal-Associated Phosphorus to Bioavailable Phosphorus in Surface and Core Sediments in the East China Sea

To improve the burial flux calculations of bioavailable phosphorus （P） and study opal-associated P （Opal-P） in the East China Sea （ECS）, surface and core sediments were collected in the Changjiang Estuary （CE） and the south of the Cheju Island. In this study, sedimentary P was operationally divided into seven different forms using modified sedimentary extraction （SEDEX） technique： LSor-P （exchangeable or loosely sorbed P）, Fe-P （easily reducible or reactive ferric Fe-bound P）, CFA-P （authigenic carbonate fluorapatite and biogenic apatite and CaCO3-bound P）, Detr-P （detrital apatite）, Org-P （organic P）, Opal-P and Ref-P （refractory P）. The data revealed that the concentrations of the seven different P forms rank as Detr-P 〉 CFA-P 〉 Org-P 〉 Ref-P 〉 Opal-P 〉 Fe-P 〉 LSor-P in surface sediments and CFA-P 〉 Detr-P 〉 Org-P 〉 Ref-P 〉 Fe-P 〉 Opal-P 〉 LSor-P in core sediments. The distributions of the total phosphorus （TP）, TIP, CFA-P, Detr-P are similar and decrease from the CE to the south of the Cheju Island. Meanwhile, Org-P and Opal-P exhibit different distribution trends; this may be affected by the grain size and TOM. The concentrations of potentially bioavailable P are 9.6-13.0 μmol g^-1 and 10.0-13.6 μmol g^-1, representing 61%-70% and 41%？64% of the TP in surface and core sediments, respectively. The concentrations of Opal-P are 0.6-2.3 μmol g^-1 and 0.6-1.4 μmol g^-1 in surface and core sediments, ac-counting for 5.3%？19.8% and 4.2%？10.6% of bioavailable P, respectively. The total burial fluxes of Opal-P and bioavailable P are 1.4×10^9 mol y^-1 and 1.1×10^10 mol yr^-1 in the ECS, respectively. Opal-P represents about 12.7% of potentially bioavailable P, which should be recognized when studying P cycling in marine ecosystems.

A Review on Effects of Personalized Ventilation Systems on Air Quality and Thermal Comfort in Aircraft Cabin Mini-Environments

This study conducts an evaluation of air quality,dispersion of airborne expiratory pollutants and thermal comfort in aircraft cabin mini-environments using a critical examination of significant studies conducted over the last20 years.The research methods employed in these studies are also explained in detail.Based on the current literature,standard procedures for airplane personal ventilation and air quality investigations are defined for each study approach.Present study gaps are examined,and prospective study subjects for various research approaches are suggested.

Lightweight SOA-Based Twin-Engine Architecture for Enterprise Systems in Fixed and Mobile Environments

Mobile devices as a popular computing platform for enterprise systems have enabled certain tasks to be executed out of office.However,the work may be interrupted due to the server shutdown or network disconnection when employees access traditional single-engine Business Process Management System.To overcome this defect,we present a lightweight twin-engine architecture based on Service Oriented Architecture(SOA).In this paper,we discuss in detail the design and implementation of the architecture,and present a trigger mechanism to activate engines according to the states of hybrid environments since it is critical for the two types of engines to cooperate closely in hybrid environments with fixed and mobile computing resources.The experimental results validate the usability of the architecture.

Numerical simulation and optimization of red mud separation thickener with self-dilute feed

In order to acquire the flow pattern and investigate the settling behavior of the red mud in the separation thickener,computational fluid dynamics(CFD),custom subroutines and agglomerates settling theory were employed to simulate the three-dimensional flow field in an industrial scale thickener with the introduction of a self-dilute feed system.The simulation results show good agreement with the measurement onsite and the flow patterns of the thickener are presented and discussed on both velocity and concentration field.Optimization experiments on feed well and self-dilute system were also carried out,and indicate that the optimal thickener system can dilute the solid concentration in feed well from 110 g/L to 86 g/L which would help the agglomerates' formation and improve the red mud settling speed.Furthermore,the additional power of recirculation pump can be saved and flocculants dosage was reduced from 105g/t to 85g/t in the operation.

Experimental Studies of the Effect of Wall Roughness on Particle Behavior in Gas-Particle Flows

The effect of wall roughness on particle behavior in two-phase flows in a horizontal backward-facing step is studied using a phase-Doppler particle anemometer. The results show that the wall roughness widens the particle velocity probability density distribution, enhances the redistribution of particle velocity into different directions, reduces the particle longitudinal mean velocity and increases the longitudinal and transverse fluctuation velocities and Reynolds shear stress. The effect of roughness on particle motion in the recirculation zone is weaker than that in the fully developed flow region. The effect of roughness for small particles is restricted only in the near-wall region, while that for large particles diffuses to the whole flow field.

Digital Forensic Analysis on Runtime Instruction Flow

Computer system＇s runtime information is an essential part of the digital evidence. Current digital forensic approaches mainly focus on memory and I/O data, while the runtime instructions from processes are often ignored. We present a novel approach on runtime instruction forensic analysis and have developed a forensic system which collects instruction flow and extracts digital evidence. The system is based on whole-system emulation technique and analysts are allowed to define analysis strategy to improve analysis efficiency and reduce overhead. This forensic approach and system are applicable to binary code analysis, information retrieval and matware forensics.

Numerical simulation of the hydrodynamics within octagonal tanks in recirculating aquaculture systems

A three-dimensional numerical model was established to simulate the hydrodynamics within an octagonal tank of a recirculating aquaculture system. The realizable k-e turbulence model was applied to describe the flow, the discrete phase model （DPM） was applied to generate particle trajectories, and the governing equations are solved using the finite volume method. To validate this model, the numerical results were compared with data obtained from a full-scale physical model. The results show that： （1） the realizable k-e model applied for turbulence modeling describes well the flow pattern in octagonal tanks, giving an average relative error of velocities between simulated and measured values of 18% from contour maps of velocity magnitudes; （2） the DPM was applied to obtain particle trajectories and to simulate the rate of particle removal from the tank. The average relative error of the removal rates between simulated and measured values was 11%. The DPM can be used to assess the self-cleaning capability of an octagonal tank; （3） a comprehensive account of the hydrodynamics within an octagonal tank can be assessed from simulations. The velocity distribution was uniform with an average velocity of 15 cm/s; the velocity reached 0.8 m/s near the inlet pipe, which can result in energy losses and cause wall abrasion; the velocity in tank corners was more than 15 cm/s, which suggests good water mixing, and there was no particle sedimentation. The percentage of particle removal for octagonal tanks was 90% with the exception of a little accumulation of 〈5 mm particle in the area between the inlet pipe and the wall. This study demonstrated a consistent numerical model of the hydrodynamics within octagonal tanks that can be further used in their design and optimization as well as promote the wide use of computational fluid dynamics in aquaculture engineering.

Effect of auxiliary ventilations on diesel particulate matter dispersion inside a dead-end entry

Diesel particulate matter(DPM) is considered carcinogenic after prolonged exposure. This paper used computational fluid dynamics(CFD) method to study the effect of four auxiliary ventilation systems on DPM distribution in a dead-end entry with loading operation. The auxiliary ventilation systems considered include: blower fan and tubing; exhaust fan and tubing, jet fan, and push–pull system. A species transport model with buoyancy effect was used to examine the DPM dispersion pattern with unsteady state analysis. During the 200 s of the loading operation, high DPM levels were identified in the face and dead-end entry regions. This study can be used for mining engineer as guidance to design and setup of local ventilation. It can also be used for selection of DPM control strategies and DPM annual training for underground miners.

Quantum Computation with Two-Level Systems in Current-Biased Josephson Junction

We present a feasible scheme that realizes quantum computation using the two-level systems （TLSs） in Current-biased Josephson junction （CBJJ） under the present experimental technology. Effective manipulation of the TLSs by CBJJ serving as register qubit can be obtained, such as initialization, single-qubit rotations, two-qubit gates, entanglement generation, and read out, etc. In addition, we also discuss the experimental feasibility and efficiency of the scheme.

CFD aided investigation of single droplet coalescence

This article describes the development of a coalescence model using various CFD work packages,and is validated using as toluene water model system.Numerical studies were performed to describe droplet interactions in liquid–liquid test systems.Current models use adjustable parameters to describe these phenomena.The research in the past decades led to different correlations to model coalescence and breakage depending on the chemical system and the apparatus geometry.Especially the complexity of droplet coalescence requires a detailed investigation of local phenomena during the droplet interaction.Computational fluid dynamics(CFD) studies of single droplet interactions were performed and validated with experimental results to improve the understanding of the local hydrodynamics and film drainage during coalescence.The CFD simulations were performed for the interaction of two differently sized droplets at industrial relevant impact velocities.The experimental verification and validation of the numerical results were done with standardized high-speed imaging studies by using a special test cell with a pendant and a free rising droplet.An experimental based algorithm was implemented in the open source code OpenF OAM to account for the contact time and the dimple formation.The standard European Federation of Chemical Engineering(EFCE) test system toluene/water was used for the numerical studies and the experimental investigations as well.The results of the CFD simulations are in good accordance with the observed coalescence behavior in the experimental studies.In addition,a detailed description of local phenomena,like film rupture,velocity gradients,pressures and micro-droplet entrainment could be obtained.

Effect of floor level slit exhaust ventilation system on distribution of house dust

Based on the fact that the house dust usually falls on the ground, the floor level slit exhaust ventilation system including inlet located at the ceiling and outlet of slit exhaust installed at comer between wall and floor was considered. Experiments and simulations were performed to investigate the flow and diffusion fields that are affected by this floor level slit exhaust ventilation system. The characteristics of airflow with experiments and computation fluid dynamics （CFD） are generally similar except airflow at the location of impinging flow and the location right below the inlet. Riboflavin particles were used as the house dust. For the spatial distribution of riboflavin particles in the ventilation system before operation, due to the influence of gravity, different sizes of particles show smooth decay curve. After floor level slit exhaust ventilation system is operated, the decay rate of the particles becomes faster than that after the ventilation system is powered on, and the particles with diameter of 0.5-3.0 μm in the experimental data and calculated values show good agreement.

Painlevé Analysis and Darboux Transformation for a Variable-Coefficient Boussinesq System in Fluid Dynamics with Symbolic Computation

The new soliton solutions for the variable-coefficient Boussinesq system, whose applications are seen influid dynamics, are studied in this paper with symbolic computation. First, the Painleve analysis is used to investigateits integrability properties. For the identified case we give, the Lax pair of the system is found, and then the Darbouxtransformation is constructed. At last, some new soliton solutions are presented via the Darboux method. Those solutionsmight be of some value in fluid dynamics.

Service-based flexible workflow system for virtual enterprise

Using the services provided by virtual enterprises, we presented a solution to implement flexible inter-enterprise workflow management. Services were the responses of events that can be accessed programmatically on the Internet by HTTP protocol. Services were obtained according to some standardized service templates. The workflow engine's flexible control to a request was bound to appropriate services and their providers by using a constraint-based, dynamic binding mechanism. Hence, a flexible and collaborative business was achieved. The workflow management system supports virtual enterprise, and the styles of virtual enterprises can be adjusted readily to adapt various situations.

THE METHOD OF DATA PROCESSING OF THE ELECTRICAL SURVEYING AND THE PROGRAM SYSTEM USED ON MICROCOMPUTER

The ESS software package is prepared for electrical data processing in the fields of coal prospecting, hydrogeologicai engineering, and can be used in the other fields of electrical data processing. It can be operated on any kind of microcomputer which has an internal memories of more than 512kB.The ESS software package would be leading the office operation to an automatic data processing period and the field work free from the tedious, repeated data treating and mapping, so that the engineers would have more time to analyse and interpret field data. Undoubtedly, it is of benefit to improving the relibility of the geological evaluation.

Feature Solution in the Process of Parameterizing Port Model

Aimed at attaining to an integrated and effective pattern to guide the port design process, this paper puts forward a new conception of feature solution, which is based on the parameterized feature modeling. With this solution, the overall port pre-design process can be conducted in a virtual pattern. Moreover, to evaluate the advantages of the new design pattern, an application of port system has been involved in this paper; and in the process of application a computational fluid dynamic analysis is concerned. An ideal effect of cleanness, high efficiency and high precision has been achieved.

Small Scale Refrigerators and Freezers： Thermal Improvements in the Envelope

Like in other sectors of activity, the sustainability in refrigeration systems is a mandatory goal to achieve, namely at house holdings, bars and restaurants, where small-scale refrigerators and freezers are widely used. The aim of this work is to demonstrate experimentally, trough measurements carried out in these equipments, the improvement that can be achieved if several modifications are implemented in traditional household refrigeration systems. In addition, it was also simulated and analysed experimentally a slightly different equipment, a refrigeration system used for draught beverages. Both systems work on a single vapour compression refrigeration with R-134a as working fluid. In the end, by implemented the modifications tested in the virtual model, it was possible to improve their thermal behaviour, a decrease in electrical energy consumption, as well as, the associated CO2 emissions reduction can be attained. In this project, the CFD （Computational Fluid Dynamics） soffware--ANSYS Fluent was used to simulate the ambient temperature and velocity fields inside the refrigerator and in that way to validate the measured results.