Preferences and willingness to pay for close to home nature for outdoor recreation in Sweden

In Sweden there is a strong tradition of using nature areas for outdoor recreation. This paper reports on a study which explored preferences and willingness to pay for outdoor recreation close to home (≤100 km away from home and ≤24 hours stay at a recreation site) using the contingent valuation method. The data originated from a mail survey that involved Swedish residents who were randomly selected from a national register. An ordinary least squares regression model was used to account for factors influencing willingness to pay. The results showed that approximately 50% of the respondents used nature areas close to their home for recreation and their average frequency of visits to these areas was 74 times annually. Areas dominated by forests were the most preferred, followed by water. The respondents were willing to pay approximately 7200 SEK (US$1080) annually. Their willingness to pay was influenced by factors such as type of nature area, distance to and time spent at the recreation site and income. The results provide one input to the land use planning process by considering the demand for nature-based outdoor recreation close to home.     

Policy design,spatial planning and climate change adaptation: a case study from Australia

There are gaps in the existing climate change adaptation literature concerning the design of spatial planning instruments and the relationship between policy instruments and the sociopolitical barriers to adaptation reform. To help address this gap, this article presents a typology of spatial planning instruments for adaptation and analyses the pattern of instrument choice in Australian planning processes in order to shed light on contextual factors that can impede adaptation. The analysis highlights how policy design can amplify the barriers to adaptation by arranging policy actors in ways inimical to reform and stripping decision makers of the instruments necessary to make and sustain desired policy changes.     

基于树木地貌法重建山洪泥石流历史事件--以北京密云区龙潭沟流域为例

认识区域山洪泥石流活动史是预测未来气候变化背景下灾害发展趋势的基础。利用树轮中的生长干扰信息,可以对未知山洪泥石流历史事件准确定年。本文以北京市密云区龙潭沟流域的曹庄子沟和合峪沟两条泥石流沟为研究对象,利用树木地貌学方法,在已知灾害年基础上获取阔叶树杨树的树轮生长扰动百分比,再重建未知灾害年并进行验证。结果表明:树轮对灾害的响应要滞后一年;2011年曹庄子沟的山洪导致该沟流通区、左岸、右岸和堆积区的树轮生长扰动百分比分别为-30.59%、43.78%、43.47%、-30.44%;2016年曹庄子沟的泥石流导致该沟四个分区的树轮生长扰动百分比分别为-46.08%、-45.15%、-46.64%、-37.32%。根据上述结果,推求并验证了曹庄子沟其他灾害年为2002、2013年,合峪沟灾害年为1997、2002、2011、2013、2016年。研究区1997、2002、2011、2013、2016年的响应树比例分别为35.42%、66.07%、46.43%、32.14%、58.93%,利用响应树比例能够区分灾害严重年份和次严重年份。2010年至今,该流域山洪及泥石流灾害活动频数有所增大,未来该流域再发生山洪泥石流灾害可能性仍较大。     

套箍加固RC轴压中长柱的承载力理论研究∗

为研究套箍加固RC轴压中长柱的承载力理论计算分析方法,采用切线模量理论,根据材料本构关系和内外力平衡条件,推导了套箍加固RC轴压中长柱的弹塑性稳定承载力计算方法。将理论计算结果与试验结果进行了对比分析,结果表明:理论计算值均低于实测值,且二者的偏差在15%以内。根据所推导的计算分析方法,研究了核心柱初始荷载水平β、柱子长细比l0/b、套箍层混凝土强度、套箍层配筋量四种参数对加固柱承载力Nu的影响规律,结果表明:Nu总体上随β增大而减小,当β<0.7时,减小趋势不够明显,β>0.7后,减小趋势变得明显;l0/b对Nu有明显影响,Nu随l0/b的增大而减小,但二者不是线性关系;Nu随套箍层混凝土强度提高而增大,随套箍层配筋量增大而增大。     

Prediction of gas explosion pressures: A machine learning algorithm based on KPCA and an optimized LSSVM

A gas explosion, as a common accident in public life and industry, poses a great threat to the safety of life and property. The determination and prediction of gas explosion pressures are greatly important for safety issues and emergency rescue after an accident occurs. Compared with traditional empirical and numerical models, machine learning models are definitely a superior approach. However, the application of machine learning in gas explosion pressure prediction has not reached its full potential. In this study, a hybrid gas explosion pressure prediction model based on kernel principal component analysis (KPCA), a least square support vector machine (LSSVM), and a gray wolf optimization (GWO) algorithm is proposed. A dataset consisting of 12 influencing factors of gas explosion pressures and 317 groups of data is constructed for developing and evaluating the KPCA-GWO-LSSVM model. The results show that the correlations among the 12 influencing factors are eliminated and dimensioned down by the KPCA method, and 5 composite indicators are obtained. The proposed KPCA-GWO-LSSVM hybrid model performs well in predicting gas explosion pressures, with coefficient of determination (R²), root mean square error (RMSE), and mean absolute error (MAE) values of 0.928, 26.234, and 12.494, respectively, for the training set; and 0.826, 25.951, and 13.964, respectively, for the test set. The proposed model outperforms the LSSVM, GWO-LSSVM, KPCA-LSSVM, beetle antennae search improved BP neural network (BAS-BPNN) models and reported empirical models. In addition, the sensitivity of influencing factors to the model is evaluated based on the constructed database, and the geometric parameters X1 and X2 of the confined structure are the most critical variables for gas explosion pressure prediction. The findings of this study can help expand the application of machine learning in gas explosion prediction and can truly benefit the treatment of gas explosion accidents.     

流域生态补偿标准的确定——以渭干河流域为例

生态补偿标准的确定是流域生态补偿机制构建的关键问题之一。文章构建了流域生态补偿标准的测算内容与流程,并以渭干河流域为例,计算了流域上下游生态损益、 居民支付意愿和综合成本,分别作为补偿的最高、 最低和参考标准。结果表明:2007年上游应获得的最高补偿标准为24.83×10⁸元,最低标准为2 443.46×10⁴元,参考标准为6.7×10⁸元。下游各县作为受益者,应支付的补偿额为:库车为818.51×10⁴~28 096.3×10⁴元,补偿参考标准19 927.61×10⁴元;沙雅466.7×10⁴~64 179.1×10⁴元,补偿参考标准17 204.17×10⁴元;新和341.17×10⁴~155 988.7×10⁴元,补偿参考标准为29 998.71×10⁴元。不同补偿标准对流域农牧民福祉产生较大影响,按照参考标准的8.67%进行补偿,就可使上游居民尤其是水源涵养区的农牧民收入水平可有较大程度的提高,达到流域的平均收入水平。在讨论部分对流域生态补偿标准测算中面临的难题进行了分析。     

悬浮填料生物流化床在城镇污水厂的应用

采用悬浮填料生物流化床对城镇生活污水进行处理,通过调试掌握该工艺的技术控制要点,并对该工艺去除污染物的效果进行分析。实践应用表明,该装置能有效去除生活污水中的BOD、COD、NH3-N、TP、SS等污染物成分,出水水质达到《生活杂用水标准》的相关排放标准,并取得了良好的经济和环境效益。     

Preliminary techno-economic analysis of three typical decentralized composting technologies treating rural kitchen waste: a case study in China

● Decentralized composting (DC) is a profitable KW treating technology. ● SAC and BEC were economically attractive in rural area, while HDC was unprofitable. ● KW handling subsidy plays a vital role in making DC profitable. ● SAC and BEC have great potential in promoting rural KW treatment. This study was designed to evaluate whether the decentralized rural kitchen waste (KW) composting technologies used in China can be widely applied. To this end, we completed a techno-economic analysis of three typical types of KW compositing, namely solar-assisted (SAC), bio-enhanced (BEC), and heat-dewatering composting (HDC). These evaluations revealed that all three technologies produce composting products that meet China’s organic fertilizer standard and that both SAC and BEC are economically self-sustaining and generate net profits (18824.94 and 17791.52 US$/a) and positive net present values (32133.11 and 25035.93 US$). Subsequent sensitivity analysis demonstrated that the KW-handling subsidy plays a critical role in making decentralized composting economically attractive. Based on these analyses, we believe that reducing the coverage area of SAC, reducing the operating cost of BEC and HDC, upgrading composting products, and strengthening secondary pollution control would aid in supporting the technological improvement of these processes. Moreover, providing appropriate subsidies and promulgating specific standards and policies for KW fertilizer are key strategies for decentralized rural KW composting management.     

Evaluation of guardrail systems for preventing falls through roof and floor holes

Introduction

Fall-related occupational injuries and fatalities are serious problems in the U.S. construction industry, especially incidents related to unguarded holes. The National Institute for Occupational Safety and Health, Division of Safety Research, Morgantown, WV conducted a project to evaluate the effectiveness of guardrail systems to prevent falls through roof and floor holes.

Methods

Two commercial edge-protection products were evaluated when used as perimeter guarding around a roof hole. Installations of the commercial products were compared to job-built guardrails constructed of 2^″ × 4^″ construction-grade lumber. Occupational Safety and Health Administration (OSHA) regulations require that “a force of at least 200 pounds” must be supported by the top rail of a guardrail system “in any outward or downward direction at any point along the top edge.” A laboratory testing system was developed to evaluate this requirement. A dynamic 200-lb force was generated against the top rail using a weighted manikin mounted on a hinged steel frame. Nine construction workers, who served as test subjects, each built five different guardrail configurations.

Results

All 45 configurations met the 200-lb OSHA requirement. Installation time for one commercial product was 32% quicker than the job-built configuration (25.6 min vs. 37.9 min).

Impact on Industry

This study: (a) indicates that the two edge-protection products can be used as perimeter guarding; (b) highlights the importance of using proper materials and fasteners to construct guardrails to protect workers from falling into unguarded roof and floor holes; and (c) discusses an overall-strength-testing methodology that can be used by fall-protection researchers.     

The NIOSH Construction Program: Research to practice, impact, and developing a National Construction Agenda

The U.S. National Institute for Occupational Safety and Health (NIOSH) conducts research to improve and protect the health and safety of workers. This paper describes the experience of the NIOSH Construction Program with two recent program planning initiatives intended to improve the program: (a) an independent external review of work over the past decade and (b) the development of strategic goals organized into a “National Construction Agenda” to guide a decade of future work. These goals, developed with input from construction industry stakeholders and researchers, are a part of the NIOSH National Occupational Research Agenda (NORA) initiative. The NORA goals are intended to provide an ambitious set of goals for all construction stakeholders to work together on. Both efforts relate to insuring the relevance and impact of research, reflecting an emerging policy perspective that research programs should be judged not just by the quality and quantity of science produced, but by the industry impact and tangible benefit resulting from the research. This paper describes how views on research planning have evolved to incorporate lessons learned about how research leads to improved safety and health for workers. It also describes the process used to develop the goals and the resulting strategic and intermediate goals that comprise the National Construction Agenda.