A generalised back-flow model to predict the tracer response in liquid—liquid stagewise contactors

A generalized transient back-flow model to predict the transient tracer concentration in a multistage extraction column has been developed. The model does not assume any extra stage at the end of the contactor and is based on unified formulation. The solution can be obtained in a straight forward way by using the linear operator theoretic approach as opposed to Laplace transform.     

Investigation of Diamond Synthesis from a Mixture of an Explosive with a Carbon Additive Using a Tracer Technique

The synthesis of detonation diamonds from a mixture of RDX labeled by C¹⁴ isotope with soot was studied experimentally. It was shown that a considerable portion of the diamonds (24.7 ± 3.4)% are formed from the carbon of RDX molecules. The degree of conversion of the carbon atoms of soot to the diamond phase is (16.0 ± 1.6)%. __________ Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 5, pp. 117–118, September–October, 2005.     

Measurement of heat and mass transfer between the lower and upper floors of a house

The work is concerned with measuring heat and mass transfer between the lower and upper floors of a conventional house via a doorway. Air flows between the two floors were measured using a single tracer gas technique, and the temperatures at various points in each floor were measured using thermocouples. The lower floor of the house was heated to various temperatures in the range 18–35 °C using thermostatically controlled heaters. The upper floor was unheated. Two portable SF₆ systems fitted with electron capture detectors were employed for measurement of the interzonal air flow. The mass and heat flow rates between the two floors were calculated from the tracer gas concentrations, and temperature differences and results were compared with the values predicted by the existing algorithms for the two zone enclosures. The mass flow rate and coefficient of discharge for the doorway were found to be functions of the temperature difference between the floors of the house.     

Analytical model for tracer transport in reservoirs having a conductive geological fault

Geological faults are frequently found in oil reservoirs and their presence dramatically impacts the underground fluid motion. Tracer tests provide a mean to dynamically characterize the conduit or barrier behavior of the fault. Although diverse analytical models have been developed to describe tracer transport in a geological conductive fault, only few of them capture the fact that injection and production wells are regularly located outside the fracture plane. In many cases, the tracer path length outside the fault structure is significant. In this work the system is represented by three coupled regions associated to the injector-to-fault, fault, and fault-to-production-well zones. The coupling is simplified by considering linear flow and aligned regions. This model includes hydrodynamic dispersion, an important phenomenon not considered in previous work. One-dimensional advective–dispersive tracer transport is assumed in each region. Border conditions require tracer mass conservation. The initial condition is a Dirac delta pulse at the injection site. The equations are analytically solved in Laplace space and the inverse transform is evaluated numerically by the Stehfest algorithm. Four specific cases have been studied; they comprehend a long and a short fault path length having low or high dispersivity respectively. The pulse behavior and the tracer breakthrough curve, as well as their sensitivity to fault dispersion, fault length and fault fluid velocity are analyzed. Clear differences in the pulse profile and breakthrough curve shape are found in relation to the case when no fault is present.     

Applications of the concept of river tracer data similarity

The response of a river to a pollution incident is heavily influenced by the river's flow rate. To capture the full range of this response, tracer experiments are often used. The paper discusses how the concept of similarity of temporal concentration profiles can be used to better exploit the information content of such experiments. Examples are given showing that poor quality tracer data that might be thought to be of little use may yet contain valuable information. Extracting this information has the potential of improving predictions of pollutant travel times, in particular, as well as offering the prospect of improving estimates of flow rates (via dilution gauging) and dispersion coefficients (via several methods).     

地下水连通介质结构分析——以寨底地下河系统实验基地示踪试验为例

对寨底地下河系统北部区域进行示踪试验,确认了北部区域的地下水分水岭边界。进一步对示踪试验数据进行详细分析,推测得到从投放点G06到排泄点G16、G20之间的地下水连通介质结构,其中G06～G16段以管道介质为主并发育一条支道和一个以上溶潭,G16～G20段含水介质则以裂隙为主。最后依据投放量、最大检测浓度等建立相对浓度系数概念,并用于分析比较G06至G16、G16至G20两段不同含水介质条件下的地下水流的径流集中程度。     

FASTRAK在高密度头相关传输函数测量中的应用

高密度头相关传输函数测量对声源空间方位的精度有更高要求,因此要有精度较高的声源定位装置（系统）,并对定位系统的误差进行校准。使用FASTRAK电磁追踪器对测量高密度HRTF的定位系统进行误差校准。FASTRAK的空间分辨率为0.01°,静态精度为0.15°,经定位系统精度校准后,声源方位角误差可控制在0.1°±0.15°的范围内。文中测量高密度HRTF数据库的最小方位角间隔为2.5°,上述误差基本满足测量要求。     

A sensitive and selective direct competitive enzyme-linked immunosorbent assay for fast detection of Sudan I in food samples

BACKGROUND: Sudan I, a synthetic azo dye, is considered to be a genotoxic carcinogen and is prohibited in foodstuffs for any purpose at any level worldwide. In this study, a sensitive and specific direct competitive enzyme‐linked immunosorbent assay (dc‐ELISA) for fast detection of Sudan I in food samples was developed for the first time. The monoclonal antibody against Sudan I was used as capture protein, while horseradish peroxidase labeled Sudan I conjugate prepared by the periodate method via ovalbumin (OVA) as a bridge was used as enzyme tracer. RESULTS: The standard curve of dc‐ELISA for Sudan I was constructed in the range 0.1–100 ng mL^?1 and the assay time was within 80 min. Sensitivity was 2.6 ng mL^?1 and the limit of detection was 0.08 ng mL^?1. Cross‐reactivity values of the assay with Sudan II, III and IV were 5.78%, 1.72% and 0.64%; no cross‐reactivity was found with six other edible colorants. The assay was tolerated to 30% of methanol and 10% of acetonitrile without significant loss of IC₅₀. Recoveries of spiked Sudan I in five different samples including chilli powder, tomato sauce, hotpot seasoning and chilli sauce I and II were within 88.4–113.2% and the intra‐assay relative standard deviation was less than 14%. The dc‐ELISA was confirmed by conventional high‐performance liquid chromatography and the correlation coefficient of the two methods was 0.9902. CONCLUSION: The proposed dc‐ELISA method provides an alternative method for sensitive, specific and fast determination of Sudan I in food samples. Copyright © 2011 Society of Chemical Industry     

南泥湖露天矿区采场水力联系及矿坑涌水量预测

为了查明南泥湖露天矿区采场范围内水力联系及矿坑涌水量,分析了含水层类型及其富水性特征,地下水补给、径流、排泄条件,地下水的基本特征等,基于此,采用长期水文监测、示踪试验及水化学分析等方法,研究了大气降水、地表水、地下水及矿坑涌水之间的水力联系及相互转换关系;并分析了露采矿坑的涌水因素以及预测了露采矿坑涌水量,主要包括矿坑大气降水补给量、地表径流量和地下水补给量。研究为后期水文地质监测以及地质灾害防治提供了技术支持。     

Mobile Agent-Based Memory Tracer Using Host-Based Intrusion Detection System for Safeguarding Critical Memory

ABSTRACT

Intrusion in a host may cause damage to the critical memory, which contains important official files or databases. The mobile agent, a piece of code that makes parallel run on host, migrates through the network and performs the requested action. In this paper, we declare a new intrusion detection model using Host-Based Intrusion Detection System (HIDS) for identification and recovery strategies. A memory trace model has been designed to identify the intrusion detection by using a memory tracer mobile agent. Memory Checksum plays a vital role in the identification of the intrusion. This model is designed for intrusion into a host, which alters the critical memory.