Test run of biodiesel in public transport system in Belgrade

The problems related to our strong dependency on fossil fuels, i.e. greenhouse effect, energy dependency, urban pollution, are of growing importance in recent years. European Union (EU) Action plan of 2003, which had originated from Kyoto Agreement, defined a strategy for substitution of 20% of conventional fuel with the alternative one by 2020. Proved advantages of biodiesel usage in the system of public transport of passengers, with regard to exhaust gases emission above all, have been the decisive determinants for the actual promotion of biodiesel as ecologically “clean” fuel, while its wider usage gives important contribution to sustainable development of cities. This paper presents results of biodiesel-test run in Belgrade, as a part of the project BIO-PEX, which relates to the usage of this alternative fuel in real operating conditions in urban public transport system, with special emphasis on technical, ecological and operational aspects of biofuel usage.     

The effect of ozonization on furniture dust: Microbial content and immunotoxicity in vitro

Moisture and mold problems in buildings contaminate also the furniture and other movable property. If cleaning of the contaminated furniture is neglected, it may continue to cause problems to the occupants even after the moisture-damage repairs. The aim of this study was to determine the effectiveness of high-efficiency ozone treatment in cleaning of the furniture from moisture-damaged buildings. In addition, the effectiveness of two cleaning methods was compared. Samples were vacuumed from the padded areas before and after the treatment. The microbial flora and concentrations in the dust sample were determined by quantitative cultivation and QPCR-methods. The immunotoxic potential of the dust samples was analyzed by measuring effects on cell viability and production of inflammatory mediators in vitro. Concentrations of viable microbes decreased significantly in most of the samples after cleaning. Cleaning with combined steam wash and ozonisation was more effective method than ozonising alone, but the difference was not statistically significant. Detection of fungal species with PCR showed a slight but nonsignificant decrease in concentrations after the cleaning. The immunotoxic potential of the collected dust decreased significantly in most of the samples. However, in a small subgroup of samples, increased concentrations of microbes and immunotoxicological activity were detected. This study shows that a transportable cleaning unit with high-efficiency ozonising is in most cases effective in decreasing the concentrations of viable microbes and immunotoxicological activity of the furniture dust. However, the method does not destroy or remove all fungal material present in the dust, as detected with QPCR analysis, and in some cases the cleaning procedure may increase the microbial concentrations and immunotoxicity of the dust.     

Cooked and brined shrimps packed in a modified atmosphere have a shelf-life of >7 months at 0 °C, but spoil in 4–6 days at 25 °C

Summary Spoilage and safety of cooked, brined and modified atmosphere packed shrimps were studied at 0, 5, 8, 15 and 25 °C. Shrimps from two sources, cold and warm waters, were brined in a sodium–chloride brine containing benzoic, citric and sorbic acids. Shelf-life was above 7 months at 0 °C but only 4–6 days at 25 °C. Apparent activation energy for the effect of temperature on shelf-life was > 100 kJ mol^-1. This pronounced effect of temperature was explained by changes in spoilage microflora at different storage temperatures. Simple and empirical mathematical models for rates of spoilage were developed for the prediction of shelf-life at different temperatures. To evaluate safety, products were challenged with Listeria monocytogenes and spores of Clostridium botulinum . Above 5 °C growth responses of L. monocytogenes followed the square root model with a T_min-value of +0.2 °C. Cl. botulinum produced toxin at the time of spoilage at 25 °C but only in shrimps with < 3% water-phase salt.     

Thermophysical Properties of Fluids from Dynamic Light Scattering

In a continuous development for more than three decades, dynamic light scattering (DLS) has evolved into a versatile and powerful technique for the determination of transport and other thermophysical properties of fluids. The success is founded on its application in a macroscopic thermodynamic equilibrium, i.e., without the need for employing external gradients, to determine a large variety of properties, which can be derived, in some instances even simultaneously, by an appropriate experimental approach and a corresponding signal analysis. The principles, essential features, and variants of the technique are reviewed, and a survey on the determination of various desired transport and thermophysical properties is given, both for the application of light scattering from bulk fluids and for the variant of surface light scattering (SLS). The stage of development and the corresponding uncertainties are discussed for the measurement of the individual quantities, and the performance of the method is demonstrated by representative experimental results for relevant fluids.     

一个10ns脉冲束流传输系统

我所质子静电加速器头部切割的10ns脉冲束流经加速成0.5至2.5MeV后,传输进入中子厅,或由高频扫描板扫开,经Mobley磁铁压缩成1—2ns脉冲束流,或由Mobley磁铁偏转,在距磁铁出口1.54米处得到一横截面为圆形的束斑。它的半径为2mm,最大散角为5mrad。如图1所示,为了利用大液体闪烁探测器测量快中子俘获截面,一个10ns脉冲束流传输系统     

Mechanical stresses on cargo during ground operations in air transport

Mechanical stresses from the shocks and vibrations to which air cargo is exposed during transport and handling at airports have been investigated. Field trials were carried out at Arlanda Airport, Stockholm, and John F. Kennedy Airport, New York. It was found that when products are transported in the airport area, they are exposed to much higher stresses than during actual flight. Especially severe conditions were registered during transport at John F. Kennedy Airport. Measured stresses are related to the ground and mode of driving within the airport area, as well as to location on the pallet wagon. Guidelines as regards design of realistic, simulating test programs for product and package design are reported. Future development possibilities and suggestions for further research within the area are discussed.     

Microirrigation Lateral Design using Lateral Discharge Equation

A simple and accurate method is developed for designing single, paired, and tapered microirrigation laterals. The hydraulics of the lateral is evaluated using a lateral discharge equation approach. A simple power equation is used to express the relationship between the inlet flow rate and inlet pressure head of the lateral. Keeping the flow variation within the specified limit, a procedure for designing the length of the tapered section is developed. The lateral is designed using a step-by-step method. The length of the tapered section is determined by the golden section search method.     

热送方钢坯汽车的改造

在保持汽车原有性能的基础上 ,对普通 2 0 t O43斯太尔货运汽车进行了改制 ,重新制造了车盘、挡板墙、车门及车箱顶 ,使车辆具有保温性能 ,并使热方钢坯的装卸十分方便 ,满足了热送 12 0 mm× 12 0 mm× 5 0 0 0 mm方钢坯的工艺要求     

岩溶地区客运专线桥梁桩基础质量控制初探

溶洞地区的钻孔桩施工及桩基质量的控制一直是一个非常难的课题,而客运专线工程对其桩基的质量要求更高。武广客专线新广州站试验段新街河特大桥处于溶洞地区,沿线地质条件非常复杂。文章根据该桥施工的工程实践,提出了对客运专线桥梁工程溶洞地区桩基施工的一些具体的技术措施,保证了桩基础施工质量。     

St. Venant–Exner Equations for Near-Critical and Transcritical Flows

The solution of the St. Venant–Exner equations as a model for bed evolution is studied under conditions when the Froude number, F, approaches unity, and the quasi-steady model becomes singular. It is confirmed that the strict criterion for critical flow, the vanishing of a water surface disturbance celerity, is not met, yet the direction of propagation of a bed wave apparently changes depending on whether F>1 or F<1. An analysis of the linearized model problem for an infinitesimal bed wave under near-uniform conditions is performed, and qualitative features of the solution are brought out. Under appropriate sediment transport conditions, when F2→1, two bed waves, one traveling upstream and the other traveling downstream, are found to develop from an initially single localized bed perturbation. Simulations of the full unsteady problem were performed with the Preissmann scheme to confirm the linear analysis and to study the effects of nonlinearity and friction. A transcritical case, in which a region where F2<1 is succeeded by a region where F2>1, is also investigated, and the solution exhibits an apparently different behavior than cases where the flow is everywhere sub- or supercritical, but can be understood as a hybrid of the latter cases.