Effects of magnesium stress and temperature on the crowth and photosynthetic character of cucumber seedlings

The effects of magnesium stress on the growth and photosynthetic character of cucumber seedlings are studied at various temperatures using artificial climate box. This is done to investigate the functional mechanism of magnesium in cucumbers. The results show that at low temperature, magnesium stress evidently inhibits plant growth, while at suitable temperatures it decreases the plant diameter, total number of leaves, leaf area, and dry weight of the above ground parts, and increases the plant height and root/shoot ratio. Excessive magnesium promotes below ground cucumber growth. The value of chlorphyl A/chlorophyl B (Chla/Chlb) increases more under conditions of magnesium deficiency than under magnesium excess. The Chla, Chlb and Cxc content decreases when magnesium is deficient, increase when excessive magnesium exists at suitable temperatures, but decreases if excessive magnesium exists at low temperatures. Pn and Gs decrease under magnesium stress, and are at the lowest level when excessive magnesium exists at low temperatures. The effects of magnesium stress on Ci, WUE, Tr and Ls vary at different magnesium concentrations and temperatures. The main factor limiting photosynthesis of cucumber seedlings is non stomata factor when magnesium is deficient, but is a stomata factor if there is excessive magnesium.     

北温带干旱地区土壤-大气界面CO2通量的变化特征

采用箱法对栗钙土、灰钙土、粗骨土和山地灰褐土4种有代表性的干旱土壤表面CO2通量进行观测和研究。结果表明:森林土壤（粗骨土和山地灰褐土）的通量显著大于草原土壤（栗钙土和灰钙土）。干旱区土壤表面CO2通量的平均值为230.05 μmol/(m2·h),变化范围为-147.27～2 319.55 μmol/(m2·h)。不同土壤类型之间存在差异,粗骨土(351.82 μmol/(m2·h))山地灰褐土(347.33 μmol/(m2·h))栗钙土(193.36 μmol/(m2·h))灰钙土(162.37 μmol/(m2·h))。土壤表面CO2通量存在季节变化,趋势呈“S”形。9月份最高(516.79 μmol/(m2·h)),以土壤向大气释放为主;1月份最低(－7.09 μmol/(m2·h)),以大气进入土壤为主;具有春夏秋冬交替规律,与气候变化趋势基本一致,土壤表面CO2通量稍有后滞。全天候土壤表面CO2通量呈“山峰”形变化,04:00最小(154.13 μmol/(m2·h)),12:00最大(349.65 μmol/(m2·h)),具有昼夜交替规律,比气候日变化稍有滞后。影响土壤表面CO2通量的环境因子有地表空气温度、土壤温度（0～10 cm、10～20 cm和20～30 cm）、土壤含水量（0～10 cm、10～20 cm和20～30 cm）;其中,地表空气温度、土壤温度（0～10 cm、10～20 cm和20～30 cm）和土壤含水量（0～10 cm）分别与土壤表面CO2通量呈正相关关系,而10～20 cm和20～30 cm深度的土壤含水量与土壤表面CO2通量呈负相关关系,地表空气相对湿度与土壤表面CO2通量的关系不显著。大气与土壤之间的CO2存在双向转移机制,CO2不仅从土壤向大气转移,而且也从大气向土壤转移,热量在地球表面的差异性分布,导致温带和寒带地区的土壤具有平衡大气CO2浓度的功能,是温带、寒带地区的显著特征。      

Characteristics and Fitting Model of Structure Plane in Layered Rock Mass

In order to study the compressive failure characteristics of layered rock mass and build the corresponding theoretical model, the fast lagrangian method was adopted to address numerical simulation of the layered rock mass under tri axial compression. The relationship between compressive strength and inclination of structure plane was analyzed, and a theoretical model was proposed to describe their relationship. The test data from the foreign references were described by the theoretical model and the relationship between loading velocity and the compressive strength was analyzed. It was shown that, the fitting model can well describe the strength characteristics of stratified rock mass, which was validated by the numerical test and laboratory test. And the compressive strength of rock mass increased linearly with the increase of loading velocity.      

Stability of various height waste dumps based on nonlinear strength criterion

Coal mining waste dumps are representative artificial accumulations of bulky rock and soil material. Certain factors make these dumps possess characteristics such as self organized criticality, nonlinear shear strength of the waste accumulation. We discusse the main waste dump characteristics and subsequently produced numerical simulations of the stability of waste dumps of various heights using the Fast Lagrangian Analysis of Continua and based on the Hoek Brown nonlinear strength criterion. The simulation calculation results show that the stability is a dynamic evolving process corresponding to increasing waste dump height. Safety factors, based on a nonlinear rule, vary with the waste dump height. Theoretical analysis and calculated outcomes reveal a progressive failure rule of waste dumps, and all indicate the methods we put forward are reasonable.     

开拓辣木饲料产业的可行性和必要性分析

测定了辣木的营养成分,结果显示辣木是一种富营养植物,辣木叶中钙的含量是牛奶的26倍、铁是菠菜的4倍、钾是香蕉的10倍,锌的质量分数为6．99％、蛋白质为27％、总氨酸为19．8％、总糖为33．6％;辣木种子中蛋白质的质量分数为38％、粗纤维为73％,可以满足动物对各种营养素的需要。介绍了国内外辣木饲料的应用研究情况,在奶牛的食粮中添加辣木,可提高奶牛的摄食量、增加体重和提高产奶量,而且不会改变牛奶的质量。分析了饲料安全、粮食安全对人类健康和生活的影响。在此基础上,讨论了发展辣木饲料产业的可行性、必要性以及由此产生的经济和社会效益。     

Stability analysis method for perilous rock by fracture mechanics

Perilous rock is a type of geological disaster in mountainous areas. Research concerning perilous rock ruptures focuses on the expanding of control fissures in perilous rock under load action. Taking the control fissure in perilous rock as one crevice in a sample, a method employing fracture mechanics is established to calculate the union fracture strength factor along the rupture orientation at the terminus of a control fissure in perilous rock. The union fracture strength factor is a function of both the first and second type fracture strength factors. We define the ratio between the fracture tendency of rock and the union fracture strength factor as the stability coefficient of perilous rock. Further, it simplifies the rupture mechanism of sliding, falling, and toppling perilous rock as pressure shear and tension shear ruptures. We establish methods for calculating the first and second type fracture strength factors. The applications show that the stability status identified by the method is more reasonable and sensitive.     

Application of a Particle Swarm Optimization Algorithm in Truss Structure Optimal Design

The particle swarm optimization (PSO) algorithm developed in recent years is a stochastic optimization algorithm based on swarm intelligence. It possesses advantages such as being a simple concept, ease of implementation and low resource occupation. The PSO algorithm was adopted to solve the problem of size optimization of truss structures with stress and displacement constraints. We present the basic principle of the original PSO algorithm in detail, and then introduce a constriction coefficient to modify it. Moreover, reasonable values of the coefficients are proposed for the modified PSO algorithm. Several classical problems are solved using the modified PSO algorithm, and the results compared with those using traditional optimization algorithms and genetic algorithms. Numerical results show that the modified PSO algorithm has good convergence and stability, and can be applied to the size optimization of truss structures.     

Reducing the Heating and Cooling Energy Consumption of Buildings

Abstract:This research aims at proposing measures to enhance the energy efficiency of buildings in the city of Guiyang. A computer simulation study was conducted on the basis of a building model using the DeST software package. The indoor temperature and year round heating and cooling loads were simulated. From analysis of the simulation results and taking into account the climate of Guiyang, three measures for energy efficient buildings in Guiyang are proposed. 1) Heating is a greater priority than cooling in comfortable air conditioning system design; 2) Natural ventilation should be given priority in cooling design and adjustment during seasonal transition is important to reducing energy consumption in building cooling; 3) Insulating the building envelope and lowering the glazing ratio of walls are critical for reducing energy consumption in heating buildings. Our conclusions will be useful for guiding energy efficient building design not only in Guiyang but also in mild climatic areas of P. R. China.     

Synthesis Mode of Stress and Strain for Complexus Theory of Geomaterials Damage

Although the constitutive model for geomaterial damage has developed significantly, there is still dispute regarding the synthesis mode of stress and strain for the complexus theory of geomaterials damage. The synthesis mode of stress and strain for the complexus theory of geomaterials damage was studied in depth in light of the basic concepts of continuum mechanics. A general synthesis mode of stress and strain for the complexus theory of geomaterials damagmall. The amount of sampling could sharply decrease by using the dual sampling method. During the comparison, the supporting role exaggeration of the line element, which is used in the FEM model to simulate the initial lining and rock bolt, was found by FEM simulation. The lining element reaction forces which were greater than usual were reported in FEM analysis results. Deeply Buried Tunnel Reliability Analysis was developed on the platform of ANSYS.     

Comparative Study of Construction Project Letters of Guarantee in P. R. China and the United States

A construction project letter of guarantee is used as financial credit to insure the smooth project execution. The construction project letter of guarantee system developed over one hundred years in the United States where a comprehensive system has been established. It is proven that the system played a vital role in controlling construction industry risk in the U.S. In contrast, the system developed later in P. R. China but has played an increasing role in the Chinese construction industry. Based on a discussion of the structure, meaning and condition of the letter of guarantee system in the U.S., a suitable framework is sought to promote development of the letter of guarantee system in the Chinese construction industry.