微角轧工艺消除钢板圆头的研究

钢板圆头会增加钢板的切损量,影响成材率.采用微角轧制法可以消除钢板圆头,减少切损,增加经济效益.     

A Two-network thermomechanical model of a shape memory polymer

The aim of this work is to demonstrate a Helmholtz potential based approach for the development of the constitutive equations for a shape memory polymer undergoing a thermomechanical cycle. The model is able to simulate the response of the material during heating and cooling cycles and the sensitive dependence of the response on thermal expansion. We notice that the yield-stress of the material controls the gross features of the response of the model, and suggests that the material yields differently depending on not just the current value of the temperature but also on whether the temperature of the material dropped or increased from the previous time-step somewhat similar to the Bauschinger effect in plasticity, except that here the controlling parameter is the rate of temperature change rather than rate of plastic strain. The results of the simulation are in qualitative and quantitative agreement with experiments performed on two different shape memory polymer samples: polyurethane and epoxy resin. We find that modeling the hysteresis of the yield stress of the material during temperature changes is the key to the results.     

Compression and extension yield of an anisotropically consolidated soil

A series of undrained and drained triaxial tests were conducted to investigate the yielding behavior of anisotropically consolidated reconstituted Shanghai clay under triaxial compression and extension loading conditions. The soil was consolidated with K of 0.5, where K is the ratio of cell pressure to axial pressure. The tests included drained constant η (=q/p′) loading tests and undrained and drained triaxial compression and extension shear tests on anisotropically consolidated specimens. It was found that the anisotropically consolidated Shanghai clay obeys Rendulic’s principle under compression loading, but not under extension loading, and that the yield surface inclined inside the state boundary surface under extension loading. Moreover, the pre-yield behavior and the post-yield behavior were found to be very different under these two loading conditions (compression and extension loading). The test results confirm the validity of the sloping elastic wall theory, and the influence of anisotropic parameter β on the shape of the yield curve in the p′?v plane was also studied in the paper. Constitutive modeling methods for anisotropic consolidated soils were also discussed based on the test results.     

A study on the efficiency of a capped hardening elasto-plastic model for soft clays

It is well known that the deformation and stress-resistant characteristics of fine-grained soils, especially soft clays, are significantly influenced by the soil softness. It is therefore very important to employ a model which can accurately simulate the effects of this phenomenon. A constitutive model must be able to create a balance among stress paths, the number of parameters, the process of parameter determination, and finally, the simplicity of the computational calculations.The current study investigates the performance of a two-yield surface (cone and cap yield surface) model for soft soils. The efficiency of the cap yield surface has been studied as well. The model has been calibrated by employing the data derived from previous researches for Bangkok clay. The incorporated data have been obtained from the results of CD triaxial, CU triaxial, and oedometer tests. The proposed method for the model calibration can accurately predict the triaxial test results and oedometer test stress path simultaneously. This method for predicting the soil behavior is based on the main soil characteristics taken from common soil mechanics tests. It can be widely employed for engineering practices, especially when complicated soil behavior is encountered.     

平头压头下基体对压痕规律的影响研究

本文通过对软薄膜/硬基体两相材料体系的平头压痕弹塑性模拟.重点研究了平压头压入过程中,不同屈服强度比(软薄膜屈服强度与硬基体屈服强度之比)以及不同压头尺寸下硬基体对压痕规律的影响.研究发现硬基体对压痕规律的影响与屈服强度比近似满足线性关系,且这种线性关系不随压头尺寸的改变而改变,相同压头半径下,屈服强度比越大,影响就越明显;相同屈服强度比下,压头半径越大,影响就越小.研究还发现压头压入过程中,材料的堆积对压入深度没有影响.     

密度对大豆群体冠层微气象特征及产量的影响

以垦农4号大豆为试验材料,在大田条件下,研究了密度对大豆群体光合有效辐射强度、温度、相对湿度、CO2浓度、风速及产量的影响。结果表明：不同群体冠层的微气象特征存在差异,高密度与低密度群体之间差异显著。光合有效辐射强度及风速均随着密度的增加呈递减趋势。温度、湿度及CO2浓度具有明显的日变化规律,昼夜温差在14～17.3℃,群体的相对湿度正午12∶00时最低,高低密度群体湿度差相隔3%;群体间不同层次的CO2浓度越接近地面越高,从06∶00到12∶00时,密度为36万株/hm2的群体（即P2.4）各冠层CO2浓度均为最大。随种植密度增加,群体内单株荚数、粒数和粒重逐渐减少。当密度为36万株/hm^2时,群体产量最高。     

春播与复播油葵产量形成及群体生理参数比较研究

在新疆石河子地区,在滴灌、种植密度和田间配置方式相同的条件下,比较了春播与复播油葵品种新葵20号产量形成及群体生理参数。结果表明,春播条件下,生育期、生物产量、籽实产量、收获指数分别为97d、9271．9kg／hm^2、4349．Okg,／hm^2、0．47,复播条件下则分别为94d、14413．5kg／hm^2、4106．4kg／hm^2、0．35。春播和复播的最大叶面积指数（LAImax）分别为4．54和5．52。每公顷春播的光合势（LAD）为93．25m。d,开花后占77．6％;复播则为94．12m。d,开花后占82．9％。春、复播全生育期平均净同化率（NAR）分别为3．67、5．26g／（m^2·d）。采用更早熟的品种,提早播种,使灌浆提前,加之使用植物生长调节剂以增强光合产物向籽实转移,有望进一步提高复播油葵产量。     

国外新型梳棉机的性能特点及发展趋势

探讨国外新型梳棉机的性能特点及发展趋势。以TC11型、C70型、MK7D型梳棉机为例,对新型梳棉机的性能进行了分析,总结了新型梳棉机的性能特点、优质高产的技术措施以及新型梳棉机技术发展趋势。认为:列举的梳棉机性能基本代表了当前新型梳棉机技术发展的新特点。通过加宽工作机幅、增加梳理弧长、增加刺辊和固定盖板等梳理部件数量、提高梳理机件速度、加强清洁排杂等技术措施,以增强梳棉机的梳理能力、提高梳棉机的单产水平是新型梳棉机发展的主要趋势。     

降低催化裂化干气的几点措施

介绍了影响催化裂化装置干气产率的原因,分析总结了国内外炼厂为降低催化干气产率而采取的几种技术措施。     

Effects of Air Velocity,Air Temperature,and Berry Diameter on Wild Blueberry Drying

Abstract:

In order to design, manufacture, and commission a commercial dryer to dry individually quick frozen (IQF) wild blueberries (Vaccinium angustifolium), The Nova Scotian Fruit Company completed a series of experiments to characterize the effect of air velocity, air temperature, and packed bed depth on drying. Based on previous experience with forced air packed bed drying systems at air temperatures up to 65°C, the experiments focused on measuring the effect of air temperature and velocity during the first few hours of drying. The data collected suggest that drying occurs solely in the falling rate period. These data were used to successfully design, build, and commission a commercial dryer with a tenfold increase in production capacity over previous equipment.