Visibility Improvements with Overplow Deflectors during High-Speed Snowplowing

Windtunnel and field experiments are presented to quantify visibility improvements with deflectors that were placed over the top of snowplow blades and were designed to reduce airborne debris. Windtunnel measurements provide the influence of overplow deflectors on the distribution of debris around the truck. Road tests on airport taxiways and highways show that the visible area of the plow truck increases by about 50% for following traffic and that snow debris, which blows over the top of the plow, is eliminated with trap angles less than 50°.     

Contributors to Construction Debris from Electrical and Mechanical Work in Hong Kong Infrastructure Projects

The crucial problem of construction debris is of increasing concern in Hong Kong. In the construction industry, the electrical and mechanical (E&M) installations in the infrastructure, for example, buildings, tunnels, or dams, are some of the major and usually complex components. Difficulty in coordinating the various trades affects productivity in general, and has a major impact on the quantity of construction debris. By identifying the sources of waste at each stage of E&M engineering work, some of the construction debris can be eliminated at the source during production. This paper investigates the critical production shortcomings in the E&M sector in Hong Kong. The study is based on a survey that includes a preliminary questionnaire survey, brainstorming exercises with a focus group, structured interviews with experienced frontline supervisors, and a second focus group exercise to test findings and proposed measures. The principal findings are that “poor coordination” and “design changes and/or errors” are major contributors to variations or change orders and rework, which in turn result in a high volume of construction debris. The results also indicate that construction debris can be minimized in the E&M sector of the construction industry, if the material wastes from incidental work are reduced and also controlled better in a new work process flow pattern through recommended construction project management improvements for reducing critical production shortcomings.     

综合物化探技术在多金属硫化物找矿中的应用

在多金属硫化物矿区,通过地表岩屑地球化学测量和大功率激电中梯测量发现物化探异常,结合地质情况,对物化探异常进行综合研究分析,利用钻探工程对异常进行验证,为一条快速、准确、高效的找矿途径,值得在西北地区尤其是新疆荒漠戈壁区大力推广.     

Qinghai-Xizang Railroad Construction in Permafrost Regions

Construction of the Qinghai-Xizang Railroad (QXR) in permafrost regions presents a number of significant engineering problems. The engineering properties of permafrost can vary greatly, and climate warming, especially warm permafrost with high ice content, must be considered. Permafrost warming could induce ground ice thaw, producing embankment settlement. Consequently, thermal stability is a key consideration for the QXR construction in permafrost regions. In order to ensure permafrost thermal stability under the background of climate warming, ideas of embankment cooling to preventing permafrost change are proposed. Many methods of embankment cooling have been proposed to prevent the thawing of ground ice. For example, block-stone embankment, block and debris slope protected, thermosyphon, and special bridge designs. The amount of engineering practice and observational data testify that measurements of embankment cooling effectively decrease permafrost temperature and heighten the permafrost table beneath embankments.     

Snow Entrainment Coefficient Estimated by Field Observations and Wind Tunnel Experiments

The boundary condition for concentration of snow particles at the bed is necessary to calculate snowdrifts by a numerical analysis model. The flux type or the gradient type boundary conditions are reasonable. An idea of an entrainment coefficient of snow particle at the snow surface is useful. The values of the coefficient are considered to be a function of the density and viscosity of the working fluid and the properties of snow particles. In this paper, the values of the coefficient are estimated based on the k–ε turbulence model and the distribution of snow particle flux observed at the Mizuho Station, Antarctica in 2000, assuming the steady, fully developed flow over a flat snow surface. The snow entrainment coefficient is two or three orders smaller than the sand entrainment coefficient in a river. The reason is that the specific weight of snow particles in air is much larger than that of sand particles in water.     

Handling of Urban Snow with Regard to Snow Quality

Snow-handling strategies employed in Swedish municipalities today are not very different from those used 10?years ago. However, to reduce the environmental negative effects of snow from urban areas, such as contamination of ground water, surface water and soil, in 1990 the Swedish Environmental Protection Agency (SEPA) presented a snow-separation strategy. The separation strategy implies that the snow is separated into “heavily polluted” and “less polluted” snow. In this study, snow from different urban areas, i.e. housing areas and central areas with different traffic loads, was compared. The results show the importance of both the location and time, that is, what happens to the snow while it stays at the ground. A comparison was made with quality criteria for stormwater and for different types of recipients to establish the quality criteria required for snow to be handled in local snow deposits. To decrease, for example, municipalities’ costs for analyzing pollutants in snow, proposals for establishing standard metal concentrations in snow and for recommending snow-handling strategies were discussed.     

Snow Event Effects on Interstate Highway Crashes

This study compares snow event and equivalent nonsnow interstate vehicular crash rates and investigates weather-related elements that may contribute to crash occurrence during snow events. Vehicular crashes reported in the state of Iowa are examined on seven different sections of the interstate highway system during the 1995∕1996, 1996∕1997, and part of the 1997∕1998 winter seasons. A geographic information system was utilized to combine crash records with weather and traffic count data to obtain the data set analyzed in this study. A significant increase was observed when winter snow event crash rates on the seven interstate highway sections were compared to crash rates on those same sections during equivalent nonsnow conditions. Crash, weather, and traffic data were further analyzed to identify snow event elements that play important roles in crash occurrence on interstate highways. The results of a Poisson model for crash frequency indicated that snow event duration, snowfall intensity, and average wind speed during snow events are important contributory elements. Additionally, traffic volume during snow events was also found to be a significant factor in crash occurrence.     

Release of Impurities from Melting Snow Made from Treated Municipal Wastewater

To make snow from treated municipal wastewater is one possible polishing treatment method that can be used in cold climates. In this study, the behavior of an artificial snow pile made from treated wastewater was studied. The primary focus of the study was the release of residual contaminants into the meltwaters. It was found that the first meltwaters of the snow pack are the most concentrated with contaminants. The first 30% of the meltwaters from the snow storage area included 50% of all the impurities held in the snow pack.     

辽宁宏达金矿工程地质与环境地质浅析

在我国的经济发展中,矿业开发占据非常重要的地位。但是在矿山开采过程中,常伴发非常多的工程地质及环境地质问题,如崩塌、滑坡、泥石流、地沉地陷等,采空区塌陷等很多类型,对生态环境及自然资源造成非常严重的破坏,这些灾害的发生虽然与人类开采作业存在非常紧密的联系,但同时也和矿区工程地质及环境地质条件发密不可分。     

Mild to moderate pulmonary valvular stenosis in infant sometimes improves to the condition unnecessary to do PTPV: Doppler echocardiographic observation

Upper- and lower-case letters of the alphabet were stabilized until loss of vision occurred. Loss of straight-line visibility was the most frequently reported perceptual event. Occasionally, features of letters separated spatially before their loss of visibility. In both instances, loss of visibility often resulted in the perception of a less complex letter. Confidence ratings for each loss of letter visibility indicated that participants were quite certain about perceived fragmentations. In a control experiment, participants were asked to guess how letters would fragment during stabilization. Again, loss of line visibility was the most frequently reported event. However, spatial separation of features was rarely predicted and complex letters were not predicted to fragment into simpler letter forms. Furthermore, the confidence in predicted fragmentation was quite low. These results are consistent with the view that losses of visibility during retinal stabilization constitute a distinct perceptual experience. Fragmentations appear to be determined by the availability of less complex letter forms and by the loss of subletter information, consisting of letter features and information specifying spatial configurations.     

GPSLoc: Framework for Predicting Global Positioning System Quality of Service

While currently numerous existing engineering applications benefit from the global positioning system (GPS), it is anticipated that operation of many new, emerging applications (e.g., applications related to ubiquitous mobile computing) will rely on the information provided by this technology. Depending on the application requirement, GPS data may be collected and post-processed or collected and processed in real time. In either case, there are questions about availability, quality, and reliability of GPS data in engineering applications. To date, despite available techniques for realizing, and to some extent improving, a certain level of GPS accuracy, there is no integrated, coherent approach or technique that would provide users with solutions that combine GPS availability, quality, and reliability. To that end, we propose quality of service (QoS) assurance for GPS. With GPS QoS, users and applications would be provided with the means for predicting GPS solutions in advance meeting the requirements in a timely and cost-effective manner. We have developed a framework for the proposed GPS QoS called GPSLoc. In this paper, we discuss the requirements, methodologies, models, and algorithms for the GPSLoc framework and the experimentation with one of the GPS QoS parameters (visibility).     

Snow Characterization at a City Snow Storage Facility

A field investigation involving snow coring, surveying, and melt water collection was undertaken at a city snow storage facility to characterize the snow and melt water in Edmonton, Alberta, Canada. The investigation revealed a high content of both salts and sediment within the snow, a pile volume of 500,000?m3, a snow density of 0.63–0.83?g/cm3, and an average road salt content of 1.2 g/L within the melted snow. The salt within the Poundmaker snow pile, one of Edmonton’s five snow storage sites, represented approximately 1.5–2.0% of the total amount of salt that was used on the city roads during the 2006/2007 winter. Melt water fractionation took place on-site during the spring melt and salt concentrations in the March melt water (early spring) were often more than 10 times the concentration of the bulk snow. Some of the factors affecting the snow and melt water composition included the snow retention time on streets, snow source, weather/climate, sampling technique, and snow site characteristics/operations.     

Corporate Ethics in the Construction and Engineering Industry

Ethical conduct is closely related to legal conduct although they do not always overlap, leaving ambiguity over appropriate actions in specific circumstances. This uncertainty can be reduced by designing organizations which encourage ethical behavior. This paper investigates the organizational factors that inhibit and encourage ethical behavior in the construction and engineering industry. A total of 27 factors are identified as playing a potentially important role in influencing ethical conduct in the industry. A survey of construction firms identifies three factors as particularly influential, namely, the absence of ethics training programs; the absence of reward systems for those who act ethically within the industry, and the low level of “visibility” that exists within the industry. These findings are important for an industry that has become negatively stigmatized with poor ethical conduct. The paper concludes with a series of organizational and contractual recommendations to help the industry achieve higher standards of ethical conduct.     

Eave Ice Dams

Water seepage into interior spaces and the resultant staining of wall and/or ceiling surfaces is a common problem with eave ice dams. If the outdoor temperature is below freezing, the roof is poorly insulated, and if the roof snow layer is thick enough, the temperature at the bottom of the snow will be at freezing. A portion of the thermal energy goes into melting some of the roof snow, that is, meltwater is generated which flows downslope toward the eaves. Some of the meltwater refreezes at the cold eave, forming an ice dam. The potential for water seepage is related to the horizontal extent of the ice dam. Mitigation usually involves placing an impermeable “ice and snow guard” layer for some distance from the eave. This paper presents information on the horizontal extent of expected eave ice dams with various returns period for 15 U.S. cities. In addition a correlation between ice dam size and the 50-year ground snow load is presented which allows one to estimate ice dam size for any U.S. city.     

多规格石高强度开采矿山开拓系统的三维规划设计与施工

为了保障多规格石高强度开采矿山的石料供需平衡和安全高效生产,利用三维数字矿山软件进行矿山开拓系统的规划设计与施工监管。以舟山绿色石化基地大、小鱼山岛多规格石高强度开采工程为背景,采用3Dmine软件建立了矿区的三维数字表面模型,并进行了运输道路优化设计、开拓工程量计算等,最后进行动画模拟,分析露天矿山开拓系统的车—路协同效果,确保满足工程施工强度要求。实践表明：生成的开拓系统设计可视性好,有助于采场合理布局和石料科学调配,为多规格石的高强度开采施工奠定了技术基础。利用3Dmine数字矿山软件,设计多规格石高强度开采矿山的三维开拓系统,并将其应用于现场施工,有助于保障多规格石的供需平衡调配和矿山持续高效的生产管理。     

Role of visibility in nesting behavior of Larus gulls.

Four experiments studied 5 species of Larus gulls in England, Argentina, and the US to learn more about the relation between visibility, inter-nest distance, and aggression. Four of the species normally nest in marshes with vegetation that varies in density, structure, and placement, whereas the 5th species nests in a variety of habitats. Photographs taken with a fish-eye lens were used to measure visibility from gull nests. For all species the nearest neighbors nested in the direction of least visibility, and inter-nest distance directly related to visibility. The relation between the nearest neighbor and visibility varied for all species and related to the structure of the vegetation. Herring gulls nesting in habitats similar to those of the marsh-nesting species had equivalent relations between inter-nest distance and visibility. The amount of aggression increased when all vegetation was removed in experiments with 3 species. Given that visibility affects inter-nest distance and aggression levels, it indirectly affects the size and shape of gull territories. (47 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Accretion of Pollutants in Snow Exposed to Urban Traffic and Winter Storm Maintenance Activities. I

Urban snow is impacted by traffic activities and winter maintenance practices that result in significant accretion of dissolved, colloidal, and suspended solids in a complex heterogeneous snow matrix that includes heavy metals, inorganic, and organic compounds. Extended residence times of snow as a roadway snowbank exposed to these pollutant-generating activities lead to significant pollutant accretion and partitioning in the snow matrix. This study analyzed four highway sites in urban Cincinnati with respect to specific water quality indices for the residence time of roadway snow. Chloride levels in roadway snow illustrate a direct correlation to application of de-icing salts. While accretion of total dissolved solids (TDS) was initially rapid with a decrease late in the event, total suspended solids (TSS) accretion demonstrated a more gradually increasing trend for the duration of roadway snow, approaching 105?mg/L. Temporal trends towards increasing total chemical oxygen demand (CODt) exerted by roadway snow are similar to TSS, with CODt values approaching 105?mg/L. Applications of 2.2×105?kg of de-icing salt containing cyanide as an anticaking agent, along a 27-km section of interstate, resulted in approximately 6 kg of cyanide discharged along this major north-south interstate in the study area. Results indicate that traffic activities and winter storm management practices can have a significant impact on pollutant accretion in urban snow.     

Energy expenditure and clearing snow: a comparison of shovel and snow pusher

In order to assess the energy demands of manual clearing of snow, nine men did snow clearing work for 15 min with a shovel and a snow pusher. The depth of the snowcover was 400-600 mm representing a very heavy snowfall. Heart rate (HR), oxygen consumption (VO2), pulmonary ventilation (VE), respiratory exchange ratio (R), and rating of perceived exertion (RPE) were determined during the work tasks. HR, VE, R, and RPE were not significantly different between the shovel and snow pusher. HR averaged (+/- SD) 141 +/- 20 b min-1 with the shovel, and 142 +/- 19 beats.min-1 with the snow pusher. VO2 was 2.1 +/- 0.41.min-1 (63 +/- 12%VO2 max) in shovelling and 2.6 +/- 0.51.min-1 (75 +/- 14%VO2max) in snow pushing (p < 0.001). In conclusion manual clearing of snow in conditions representing heavy snowfalls was found to be strenuous physical work, not suitable for persons with cardiac risk factors, but which may serve as a mode of physical training in healthy adults.     

Development of a paint scheme for increasing aircraft detectability and visibility.

5 studies were performed in order to derive a paint coloration scheme which will allow maximum aircraft visibility and detectability. It was found that maximum visibility may be expected from a large, squarelike, unbroken fluorescent red-orange area and a secondary area possessing color and brightness contrast with the fluorescent red-orange. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Maximum Impact Force of Woody Debris on Floodplain Structures

We collided woody debris (i.e., logs) with structures using flume and test basin laboratory facilities to investigate the maximum impact force that floodplain structures are exposed to from floating woody debris. The tests also investigated the influence of collision geometry, determined by the debris orientation on impact, on the maximum impact forces. We reviewed the three approaches that represent the existing guidance for estimating maximum impact forces. Each approach estimates the maximum impact force based on the debris velocity and mass. We show that all the existing approaches can be derived from a single-degree-of-freedom model of the collision and can be considered to be equivalent. The laboratory data show that the maximum impact force was associated with a log striking a rigid structure with its end. Oblique and eccentric collisions reduced the maximum impact load in a predictable and consistent manner. The approach we refer to as “contact stiffness,” a linear, one-degree-of-freedom model with no damping, was able to reproduce the laboratory results over the entire range of data, with an effective contact stiffness of 2.4 MN/m.