A simple and inexpensive monitor for recording oxygen and temperature in lakes and reservoirs

The design, construction and operation of a simple and inexpensive monitor for the continuous recording of oxygen and temperature at multiple depths in small lakes and reservoirs is described. The system currently employs four electrodes suspended at selectable depths. Additional sensors can be readily incorporated into the system either to measure other “water quality” variables or to include a greater number of depths. Data is collected with a solid state multi-channel data logger.     

A simple, inexpensive in situ method for assessing acute toxicity of effluents to fish

Test chambers for conducting in situ fish bioassays were constructed from 81. polyethylene bottles. Yearling fathead minnows (Pimephales promelas) and young-of-the-year bluegill (Lepomis macrochirus) demonstrated greater than 50% survival in the chambers after 65 days of exposure in a reservoir, river and creek. Fathead minnow survival was substantially greater than that of bluegils. The chambers provide a simple, inexpensive, sensitive technique to screen effluents for toxicity.     

A simple cultivation unit for the evaluation of algal growth potential and toxicity of water

The design presented here enables a makeshift cultivation unit to be assembled for AGP evaluation after Lukavský (Lukavský J. Water Res. 17, 549–558, 1983) i.e. using solid media in a microtitration plate. The unit consists of common laboratory components and is very cheap and reliable.     

A new and simple method for recuperation of enteroviruses from water

A new and simple method for recuperation of enteroviruses from water is described here. The sample to be analyzed, with a volume arbitrarily fixed to 101, is adjusted to pH = 3.5 with hydrochloric acid. It is then injected under low pressure (0.15 bar) by the lower end of a column containing glass powder (50 g). The calibration of the water's upward speed enables the glass powder to remain in dynamic suspension. Under these conditions, poliovirus is quantitatively adsorbed on the glass powder. The virus is then eluted from the glass powder with 50 ml of a glycine buffer (pH = 11.5) and thus concentrated 200 times in the final eluate. The total duration of operation does not exceed 2 h 30 mn. The recuperation efficiency is about 40–60% and does not depend on initial virus concentration in sample, and this, for virus concentrations ranging from 1 to 10⁴PFU/1.     

A better water quality indexing system for rivers and streams

The development of a better system for indexing water quality and its application to four water use classes are described. There are three dominant use classes: bathing, water supply, and fish spawning, and one general use class. In all of them protection of aquatic life is included. To ensure that the index score tells us something useful and does not hide important information as current indexes (or indices) tend to do, the water quality variable giving the lowest score (i.e. the minimum operator) has been employed to produce the final index score. Preliminary indications are that this is a more useful aggregation method than the more commonly used additive, and multiplicative techniques. Index development has been linked to recommended water quality standards developed for New Zealand water legislation. The indexes are intended to assist in the dissemination of water quality information, particularly to lay-people.     

Concept and design of a substrata container for sampling periphyton

Limitations in available field sampling methodology and substrata sampler design criteria, to reduce retrieval losses of periphyton, are discussed. The process of retrieving submerged substrates is defined as comprising two distinct operations—(1) in situ substrata encapsulation or containment and (2) subsequent withdrawal of contained surfaces through the water column. A cylindrical closing container which effects no appreciable water disturbance on closing is described. A minimal difference was found between water movement across sampling surfaces contained in the closing system compared with traditional open-type substrata exposure devices. Comparative community sampling studies between open and closing containers in an oligotrophic lake indicate the closing containment system to be an acceptable method for studying periphyton.     

A simple method for evaluating liquefaction potential from shear wave velocity

The simplified procedure using shear wave velocity measurements is increasingly used to evaluate the seismic liquefaction potential of soils. This procedure is based on finding the boundary separating the liquefaction and non-liquefaction cases through the analysis of liquefaction case histories, following the general format of the Seed-Idriss simplified procedure based on standard penetration test (SPT) data. It is noted that many assumptions have been made in the simplified procedure. This paper develops a simple method for evaluating the liquefaction potential of soils from shear wave velocity by using the optimum seeking method to directly analyze the liquefaction history data and quantify the influence of major factors affecting the liquefactions potential of soils. The factors considered are the earthquake magnitude, the vertical effective overburden stress, the shear wave velocity, the peak acceleration at the ground surface of the site, and the fines content of the soil. The most important factor has been identified as the shear wave velocity. The developed method uses the measured data directly and in a very simple way. Neither stress-correction of shear wave velocity nor calculation of cyclic shear stress as in the simplified procedure is required. Comparisons indicate that the developed simple method has a higher success rate for evaluating liquefaction potential of soils than the simplified procedure. A case study is presented to illustrate the application of the developed simple method and further confirms its accuracy.     

A simple method for evaluating liquefaction potential from shear wave velocity

The simplified procedure using shear wave velocity measurements is increasingly used to evaluate the seismic liquefaction potential of soils. This procedure is based on finding the boundary separating the liquefaction and non-liquefaction cases through the analysis of liquefaction case histories, following the general format of the Seed-Idriss simplified procedure based on standard penetration test (SPT) data. It is noted that many assumptions have been made in the simplified procedure. This paper develops a simple method for evaluating the liquefaction potential of soils from shear wave velocity by using the optimum seeking method to directly analyze the liquefaction history data and quantify the influence of major factors affecting the liquefactions potential of soils. The factors considered are the earthquake magnitude, the vertical effective overburden stress, the shear wave velocity, the peak acceleration at the ground surface of the site, and the fines content of the soil. The most important factor has been identified as the shear wave velocity. The developed method uses the measured data directly and in a very simple way. Neither stress-correction of shear wave velocity nor calculation of cyclic shear stress as in the simplified procedure is required. Comparisons indicate that the developed simple method has a higher success rate for evaluating liquefaction potential of soils than the simplified procedure. A case study is presented to illustrate the application of the developed simple method and further confirms its accuracy.     

A simple technology for arsenic removal from drinking water using hydrotalcite

The use of a synthetically prepared clay material, hydrotalcite (HT), for the removal of arsenite (As(III)) and arsenate (As(V)) from drinking water is described. Percolation through HT of water containing 500-1000 microg/L As (levels often found in As-contaminated well water) produced leachate with As levels well below 10 microg/L. The technology could be coupled to that used in less-developed regions for removing organisms from drinking water, viz. leaching through porous pots and filter candles. The 'spent' HT is easily converted into valuable phosphatic fertilizer that would have an insignificant effect on soil arsenic levels, thereby reducing the overall cost of manufacture and distribution.     

动量插值的一种简单有效的修正

针对动量插值数学上的不足,提出一种简单的修正格式,采用与原始的SIMPLE算法非常相似的推导过程,得到不可压流体流动的一种简单的同位网格SIMPLE算法。利用有限数值算例证明新提出的同位网格算法的有效性。结果表明,所有界面速度均采用算术平均值,具有编程简单、内存占用少的优点,同时有效地克服了计算结果与松弛因子有关的的缺点,并克服了同位网格上用动量插值计算界面速度的数学上的缺陷。     

A simple conduction model for skin burns resulting from exposure to chemical fireballs

A simple conduction model is developed for skin burns resulting from a short-duration heat pulse of the type that commonly occurs with typical chemical fireballs. This model predicts the absorbed heat values necessary to produce second and third degree burns for constant heat pulses of 1 to 36 s duration. The results of the model are shown to correlate well with test data for swine and human skin.     

携手文物藏品搭建交流平台--寻求博物馆藏品沟通公众的途径

博物馆是根植于现在、保存与沟通过去的鲜活机构,将民众与其文化紧密相联,让现在和未来的人们相互理解并关照历史。面对着社会的不断发展,每个博物馆都必须认真思考自身的使命和定位,不断提升社会影响力和感召力,改进传统的藏品展示方法,更好地参与社会建设、与公众保持紧密联系。文章从藏品展示、藏品教育、藏品流通三方面对博物馆藏品沟通公众的途径予以探寻,指出挖掘文化内涵、融入观众语境;培养潜在观众、拓展想像空间;激活文化基因、创造智慧活力是博物馆与公众及社会交流、对话的有效途径。     

A model for identifying the vulnerability of streams and rivers to land use-induced changes

This article describes a model for identifying the vulnerability of streams and rivers to land-induced change. Landscape architects are frequently asked to make land use recommendations which affect landscape change. The challenge is to organize information to aid landscape architects in making responsible recommendations. This model considers three types of spatial information: (1) sources of land use-induced change; (2) intensity of drainage within watersheds; and (3) sensitivity of drainage basins to change. The model also demonstrates the use of a Geographic Information System (GIS) and its application. The strength of this model is that it provides landscape architects with both time- and cost-efficient means of assessing the vulnerability of streams and rivers with existing data. It further directs site-specific investigation to areas which are identified and prioritized with regard to the relative vulnerability of streams and rivers to land-induced change.     

A simple model for the derivation of illuminance values from global solar radiation data

This paper presents a new simple luminous efficacy model for global horizontal irradiance. The objective is to derive values of outdoor global horizontal illuminance data from typical local weather station data including global horizontal irradiance and Humidity Ratio of outdoor air. The proposed luminous efficacy model incorporates, as the main influencing variable, the Clearness Factor, which is an original derivative from the Clearness Index. Two further variables are included in the model formulation. These are the Humidity Ratio and the solar altitude. Moreover, the model includes a location-dependent variable, which may be derived from the latitude information. The paper includes the result of the statistical analysis of the relationship between the model predictions and the measured data. The results of this analysis display a good agreement between predictions and measurements.     

A simple rainfall intensity formula for Singapore

A simple rainfall intensity formula (RIF) for Singapore is proposed. Basically, it is derived from the Intensity–Duration–Frequency (IDF) curves. By applying the least squares method, the parameters of the RIF are optimised. It is convenient to apply the improved formula for programming and practical applications, compared with the conventional method of checking the IDF curves. The results furnished by the proposed formula are in very good agreement with those obtained from the IDF curves.     

Endogenous centers: A simple departure from the NUE model

The model departs from the new urban economics (NUE) by allowing a single economic agent (a G-agent, e.g., a corporate headquarters) to contact every location with equal frequency: the G-agent is allowed to travel in every direction. A NUE-like assumption requires all other agents to contact the G-agent, in which case, the G-agent must locate at the center; i.e., the CBD is necessarily endogenous. The evolution of subcenters begins with growth in demand which raises the level of bid rents by enough to outbid agriculture. After one agent moves to the suburbs, interdependency among agents insures that the incipient suburban center becomes more attractive to other agents.     

A simple method for concentrating and detecting viruses in wastewater

A simple method has been developed for routine analysis of sewage and sewage effluents for detecting viruses using adsorption at pH 3 on a 0·45 μm 47 mm diameter membrane filter and elution at pH 8. It was tested on viruses added to autoclaved sewage. Homogenizing the sample for 4 min in a Waring blender and clarification by centrifugation at 1800 g and later at 9230 g facilitated easy filtration without any loss of virus. Retention of the eluant for 30 min on the millipore membrane and then elution in situ under suction provided a sterile eluate with 100 per cent recovery of viruses.

Viruses added to fecal suspensions with 600 mg I⁻¹ BOD were completely recovered when the sample pH was adjusted to 3 and its salt concentration increased by adding 1200 mg l⁻¹ of Mg²⁺ as the chloride. This procedure eliminated the need for passing the samples through ion exchange resins for removing membrane coating components. In a 1 yr programme of monitoring of raw sewage from a middle income group community in Nagpur, a maximum of 3150 PFU/1 during monsoon and 11575 PFU/1 during winter was obtained.

High efficiency and reproducibility of the method allowed the use of sample volumes of 40 ml of raw sewage and 320 ml of treated effluent for the detection of viruses.     

一种机口简易可靠的供油装置

我们认真学习了<砖瓦>2003年第11期曹世璞<使用油机口的技术要点>和<砖瓦>2001年第1期颜志武<挤泥机机口的油润滑技术>两篇文章.结合我们的实践,找出一种利用多缸柴油机高压油泵装配机口油润滑供油系统的方法,现奉献给各位砖瓦同仁.