Design and application of a multichannel"cross"hot tearing tendency device:A study on hot tearing tendency of Al alloys

Hot tearing is one of the most serious defects during the casting solidification process.In this study,a new type of multichannel"cross"hot tearing device was designed.The hot cracks initiation and propagation were predicted by the relationship between temperature,shrinkage force and solidification time during the casting solidification process.The reliability and practicability of the multichannel"cross"hot tearing device were verified by casting experiments and numerical simulations.The theoretical calculation based on Clyne-Davies model and numerical simulation results show that the hot tearing tendency decreases in the order:2024 Al alloy>Al-Cu alloy>Al-Si alloy at a pouring temperature of 670°C and a mold temperature of 25°C.Feeding of liquid films at the end of solidification plays an important role in the propagation process of hot tearing.The decrease of hot tearing tendency is attributed to the feeding of liquid film and intergranular bridging.

Research on the overload protection reliability of moulded case circuit-breakers and its test device

This paper analyzed the reliability and put forward the reliability index of overload protection for moulded case circuit breaker. The success rate was adopted as its reliability index of overload protection. Based on the reliability index and the reli- ability level, the reliability examination plan was analyzed and a test device for the overload protection of moulded case cir- cuit-breaker was developed. In the reliability test of overload protection, two power sources were used, which reduced the time of conversion and regulation between two different test currents in the overload protection test, which made the characteristic test more accurate. The test device was designed on the base of a Windows system, which made its operation simple and friendly.

DEM Simulation to Determine the Influence on the Experimental Results of Tests of Iron Pellets When the Dimensions of the Test Device Are Varied

The current study is based on the DEM computer simulation of three experimental test devices with different dimensions to determine the difference in the results of the formation of shear and repose angles that the particles experience when grouped under the action of the gravitational force. In this respect, the experimental test devices with different height, width, and depth were geometrically modeled with iron pellet particles using morphology and a granulometric variation from 6 mm to 9 mm of equivalent diameter in its spherical shape. Depending on the results obtained, a reliable size of the experimental test device will be available to obtain the necessary data for a correct adjustment of the calibration parameters for the DEM simulation of mining-metallurgical processes that use granulated material of iron pellet.

Design and Experimental Investigation for Subsea Control Module Test System

As a core part of subsea production systems,subsea control modules(SCMs)are costly,difficult,and expensive to install and inconvenient to use in underwater maintenance.Therefore,performance and function tests must be carried out before launching SCMs.This study developed a testing device and an SCM test by investigating SCMs and their underwater.The testing device includes four parts:a hydraulic station,an SCM test stand,a signal generating device,and an electronic test unit.First,the basic indices of the testing device were determined from the performance and working parameters of the SCM.Second,the design scheme of the testing device for the SCM was tentatively proposed,and each testing device was designed.Finally,a practical measurement of the SCM,in combination with the hydraulic station,SCM test stand,signal generator,electronic unit,and highpressure water tank,was carried out according to the test requirements.The measurement mainly involved equipment inspection before testing and an experimental test for the SCM.The validity and feasibility of the testing device and method were simultaneously verified through an association test.

Study on relation between tectonic stress and coal-mining subsidence with similar material simulation

Using a minitype and stress-type test device for similar material simulation of coal-mining subsidence, the relation between tectonic stress and coal-mining subsidence was successfully simulated, furthermore, the test period of similar material simulation was obviously shortened and the test process was more dexterous and convenient. To do simi-lar material simulation with the minitype and stress-type test device was feasible and high-efficient. Bringing two models with the same geological and mining conditions to bear lateral compressive stress and tensile stress respectively and simulating the process of underground mining, the test results indicate that: under the compressive stress, the col-lapse of the coal roof occurs belatedly and the damaged range in cover of coal seam is smaller, therefore the movement and deformation of the cover and its damage to the ground geological environment are not evident; whereas under tensile stress, the situation is contrary to which mentioned above. A conclusion was obtained from the test that the ground environment hazards in coal mining areas were controlled by the regional geo-logical tectonic stress field.

Development of Ocean Energy Test Field in China

The mission of the test field is to provide technical support to associates. The paper present the development of OE （ocean energy） field in China and outline the new technologies and best practice, resources conditions, construction targets, generation device testing and standard system. The main purpose is to improve the level of China＇s ocean energy development. The Chinese ocean energy test field, which was started in 2008, involved a development divided in three phases （the overall design, construction, demonstration）. The methodology followed in the individual phases is described, and the standardization of testing wave and tidal current energy devices is introduced. The research revealed the development and the shortage of ocean energy technology in China.

An Experimental Study on Assessment of Pavement Interlayer Bond Strength

It is a common practice to apply a tack coat usually in the form of bituminous emulsion over an existing bituminous surface before laying another bituminous layer.The boundary between these two consecutive bituminous layers is the layer interface and the pavement stress distribution is highly influenced by the adhesion conditions at this interface.Poor adhesion causes adverse effects on the structural strength of the pavement system.A number of premature failures such as slippage failure and delamination failures result thus defeating the construction objectives.In the absence of a standard method and apparatus to address this field problem,an attempt has been made in this study to develop a simple testing arrangement to be used in a laboratory to determine the interlayer bond strength.Normal Marshall procedure has been used to prepare the specimens consisting of two different types of bituminous materials in lower and upper part of the same specimen.It is observed within the scope of study that Cationic rapid setting(CRS-1)emulsion applied at 0.25 Kg/m^(2) offers the best results of interlayer bond strength.

Current state and progress of research on forensic biomechanics in China

Forensic biomechanics gradually has become a significant component of forensic science.Forensic biomechanics is evidence-based science that applies biomechanical principles and methods to forensic practice,which has constituted one of the most potential research areas.in this review,we introduce how finite element techniques can be used to simulate forensic cases,how injury criteria and injury scales can be used to describe injury severity,and how tests of postmortem human subjects and dummy can be used to provide essential validation data.This review also describes research progress and new applications of forensic biomechanics in China.