Vehicle Lateral Stability Control Based on Sliding Model Control

In view of the vehicle cornering or path changing under ultimate handling maneuver, a 3-DOF nonlinear vehicle dynamics model which takes the vehicle lateral velocity, yaw rate and body roll angle as the State variables is presented. Based on the dynamic analysis, the method which using additional yaw moment produced by different longitudinal braking force among each wheels to improving vehicle handling stability in emergency situations is discussed. Considering the sideslip angle as one of the vehicle state variables is difficult to measuring, the sideslip angle estimation based on vehicle dynamic model and kinematics is designed. And then, based on the theory of siding model control, the combining sliding model control system is founded, which taking the vehicle yaw rate and body side-slip angle errors between the estimated and the real as the input variables, and taking the braking torque and the steering angle as control aims. The simulation results indicate that the control method can effectively improve the vehicle lateral handling stability.     

低分子量有机酸对促进可变电荷土壤中铝溶解的影响

Low-molecular-weight （LMW） organic acids exist widely in soils and play an important role in soil processes such as mineral weathering, nutrient mobilization and A1 detoxification. In this research, a batch experiment was conducted to examine the effects of LMW organic acids on dissolution of aluminum in two variably charged soils, an Ultisol and an Oxisol. The results showed that the LMW organic acids enhanced the dissolution of A1 in the two investigated soils in the following order： citric 〉 oxalic 〉 malonic 〉 malic 〉 tartaric 〉 salicylic 〉 lactic 〉 maleic. This was generally in agreement with the magnitude of the stability constants for the Al-organic complexes. The effects of LMW organic acids on Al dissolution were greater in the Ultisol than in the Oxisol as compared to their controls. Also, the accelerating effects of citric and oxalic acids on dissolution of A1 increased with an increase in pH, while the effects of lactic and salicylic acids decreased. Additionally, when the organic acid concentration was less than 0.2 mmol L-I, the dissolution of A1 changed Iittle with increase in acid concentration. However, when the organic acid concentration was greater than 0.2 mmol L^-1,the dissolution of A1 increased with increase in acid concentration. In addition to the acid first dissociation constant and stability constant of Al-organic complexes, the promoting effects of LMW organic acids on dissolution of A1 were also related to their sorption-desorption equilibrium in the soils.     

罗非鱼对维生素E的需要量

罗非鱼对维生素Ｅ的需要量试验的目的旨在探索鱼饲料中的脂肪含量对维生素Ｅ需要量的影响．试验１：以脂肪含量为５％、缺乏维生素Ｅ的基础饲料为对照组。在基础饲料中，添加维生素Ｅ（醋酸ＤＬ－α－生育酚）５～５０ｍｇ／１００ｇ范围内，分为４个梯度的试验组饲料，共...     

海捕回迁稻纵卷叶螟轨迹分析

利用空气粒子扩散微机模型,对1979、1980年9、10月份上海到大连航海海捕稻纵卷叶螟的回迁途径和虫源地进行模拟分析。初步明确了两年89次捕蛾中的73次虫源地。虫源主要分布于28～42°N,117～128°E 的中朝两国的沿海稻区,深入内陆或远东日本的较少。秋季回迁稻纵卷叶螟的迁飞时间变异较大:在24小时内迁来的占45.21%,经24～48小时,48～72小时迁来的蛾子分别占28.77%和24.66%,只有1.37%的虫源需72小时以上才能完成到达海捕区域的迁飞。     

油茶芽苗砧嫁接的技术环节

从生产实际出发，评述了油茶芽苗砧嫁接技术在圃地选择，选种催芽，荫棚架设，接穗选取，嫁接，栽植，栽后管理等技术环节的应用及注意事项。     

Identification of optimal regions for phylogenetic studies on VP1 gene of foot-and-mouth disease virus: analysis of types A and O Argentinean viruses

An analysis of the informative content of sequence stretches on the foot-and-mouth disease virus (FMDV) VPI gene was applied to two important viral serotypes: A and O. Several sequence regions were identified to allow the reconstruction of phylogenetic trees equivalent to those derived from the whole VPI gene. The optimal informative regions for sequence windows of 150 to 250 nt were predicted between positions 250 and 550 of the gene. The sequences spanning the 250 nt of the 3' end (positions 400 to 650), extensively used for FMDV phylogenetic analyses, showed a lower informative content. In spite of this, the use of sequences from this region allowed the derivation of phylogenetic trees for type A and type O FMDVs which showed topologies similar to those previously reported for the whole VP1 gene. When the sequences determined for viruses isolated in Argentina, between 1990 and 1993, were included in these analyses, the results obtained revealed features of the circulation of type A and type O viruses in the field, in the months that preceded the eradication of the disease in this country. Type A viruses were closely related to an Argentinean vaccine strain, and defined an independent cluster within this serotype. Among the type O viruses analysed, two groups were distinguished; one was closely related to the South American vaccine strains, while the other was grouped with viruses of the O3 subtype. In addition, a detailed phylogeny for type A FMDV is presented.     

Helminth parasites of dogs from two resource-limited communities in South Africa

Biological samples were collected from dogs in resource-limited communities in the North-West and Gauteng Provinces of South Africa to assess the prevalence of helminth parasitism. These samples included adhesive tape peri-anal skin swabs and fresh faecal samples for helminth examination, and thick and thin blood films (smears) and whole-blood samples in anticoagulant for examination of filarial nematode microfilariae and haemoprotozoa. The eggs of Ancylostoma caninum, Toxocara canis, Toxascaris leonina, Dipylidium caninum and taeniids were identified. None of the blood samples and smears tested positive for microfilariae of Dirofilaria immitis or Dipetalonema spp. or for haemoprotozoa. The adhesive tape swabs were negative for cestode eggs and segments. Most of the helminth parasites identified in this study are zoonotic and consequently are regarded as a public health hazard.