Short-term Model of the Production of Construction Aggregates in Taiwan Based on Artificial Neural Networks

BACKGROUND: Taiwan's geography and limited stock of sandstone have caused sandstone resources to gradually decline to the point of exhaustion after long-term excavation. Moreover, the Taiwanese government has continuously increased the amount of land area near rivers that cannot be excavated to facilitate riverbed remediation and promote conservation of water resources. Accordingly, predicting and managing the annual production of construction aggregates in future construction projects, and dealing appropriately with some thorny problems, for instance, demand that excess supply, excessive excavation, unregulated excavation, and the consequent environmental damage, will significantly affect the efficient use of natural resources in a manner that accords with the national policy of Sustainable Development (SD). METHODS:. This study establishes an empirical model for forecasting the annual production of future construction aggregates using Artificial Neural Networks (ANN), based on 15 relevant socio-economic indicators, such as indicator of annual consumption of cement. A sensitivity analysis is then performed on these indicators. RESULTS AND DISCUSSION: This work applies ANN to estimate the annual production of construction aggregates; the estimates, the verification of the model and the sensitivity analysis are all acceptable. Furthermore, sensitivity analysis results indicate that the annual consumption of cement is the indicator that most strongly influences the production of construction aggregates, as well as whether construction waste can be recycled and steel structures can be used in buildings, helping to reduce the future production of construction aggregates in Taiwan. CONCLUSIONS: The elaborate prediction methodology presented in this study avoids some of the weaknesses or limitations of conventional linear statistics, linear programming or system dynamics. Additionally, the results not only provide a short-term prediction of the production of construction aggregates in Taiwan, but also provide a viable and flexible means of verifying quality certification of the production data of construction aggregates in the future by incorporating those relevant socio-economic indicators. RECOMMENDATIONS AND OUTLOOK: The continuity and quality of the database of relevant indicators used in this study should be closely scrutinized in order to ensure the SD means of exploiting resources.     

基于BP网络的水质综合评价模型及其应用

讨论了BP网络模型存在的不足及建模条件,提出了建立合理的BP网络模型的基本原则和步骤.针对水质评价问题,通过在各类水质污染指标浓度区间内生成随机分布样本的方法,组成足够多用于BP网络训练、检验和测试用的样本,建立了辽河水质综合评价的BP网络模型;给出了区分不同类别水质的模型分界值样本和模型输出分界值.     

QCM传感器法定量检测空气中芥子气

搭建了可以发生不同浓度芥子气(HD)的QCM流动检测系统,芥子气浓度以气相色谱-火焰光度检测器(GC-FPD)法标定.以聚环氧氯丙烷(PECH)为敏感膜材料,建立了QCM法对芥子气样品进行定量检测的方法.探讨了膜厚度与响应频率之间的关系.在气体流速为300 mL/min时,芥子气质量浓度在1.1～52.5 mg/m3内,有良好的线性关系,方法具有较好的准确性和精密度,相对标准偏差为1.01%,最低检测限为1.1 mg/m3.并对神经性毒剂沙林(GB)的干扰进行了研究.     

Review and comparison of methods to study the contribution of variables in artificial neural network models

Convinced by the predictive quality of artificial neural network (ANN) models in ecology, we have turned our interests to their explanatory capacities. Seven methods which can give the relative contribution and/or the contribution profile of the input factors were compared: (i) the ‘PaD’ (for Partial Derivatives) method consists in a calculation of the partial derivatives of the output according to the input variables; (ii) the ‘Weights’ method is a computation using the connection weights; (iii) the ‘Perturb’ method corresponds to a perturbation of the input variables; (iv) the ‘Profile’ method is a successive variation of one input variable while the others are kept constant at a fixed value; (v) the ‘classical stepwise’ method is an observation of the change in the error value when an adding (forward) or an elimination (backward) step of the input variables is operated; (vi) ‘Improved stepwise a’ uses the same principle as the classical stepwise, but the elimination of the input occurs when the network is trained, the connection weights corresponding to the input variable studied is also eliminated; (vii) ‘Improved stepwise b’ involves the network being trained and fixed step by step, one input variable at its mean value to note the consequences on the error. The data tested in this study concerns the prediction of the density of brown trout spawning redds using habitat characteristics. The PaD method was found to be the most useful as it gave the most complete results, followed by the Profile method that gave the contribution profile of the input variables. The Perturb method allowed a good classification of the input parameters as well as the Weights method that has been simplified but these two methods lack stability. Next came the two improved stepwise methods (a and b) that both gave exactly the same result but the contributions were not sufficiently expressed. Finally, the classical stepwise methods gave the poorest results.     

Trophic relationships in the recently impounded Bagré reservoir in Burkina Faso

The trophic dynamics of Bagré reservoir which has been recently impounded in Burkina Faso was based on the data collected during 1997–1998 period using the Ecopath model and software. Total fish biomass is 22.63 t km⁻² and mainly represents trophic levels (TLs) 2 and 3. The trophic food chain is relatively long and the overall transfer efficiency is quite low. Grazing foodweb based on primary producers is prominent in the reservoir ecosystem and detritus plays a less significant role. Seasonal and long-term variations in water quality have significant influences on the lower TLs clearly showing a bottom-up functioning of the ecosystem. Environmental degradations, such as siltation occurring in the lake, suggest possible risks in limiting ecosystem productivity.     

微生物传感器快速测定BOD标准方法的技术说明

国家环保总局颁布了微生物传感器快速测定生化需氧量（BOD）的标准方法。文章主要就标准中起草过程、主要技术指标、适用范围、干扰物质、样品贮存等主要内容及实验结果加以说明。     

自组织神经网络在有害赤潮预警研究中的应用

根据非线性理论及有害赤潮的特点，探讨应用人工神经网络原理进行赤潮预警预报的方法，提出网络可塑性较强，无监督的ART－KOHONEN网络模型，阐述了其基本原理和算法。将该模型应用于辽宁省营口市鲅鱼圈海域，结果表明：该方法能较理想地解决无训练样本的分类识别问题，具有较高的精度，可用于有害赤潮的预警预报工作。     

More time in the kitchen,less time on the streets: the micropolitics of cultivating an ethic of care in alternative food networks

There is increased attention to alternative food efforts as individuals and groups seek to build stronger local food infrastructures to increase accessibility, transparency, and fairness with how food is grown, produced, and distributed. In considering individuals and families contending with food injustices and insecurities; concerns and questions have surfaced about what it means to privilege the leadership and participation of these communities in alternative food efforts. While there are no linear answers to these questions, this paper explores how one statewide food network in the United States seeks to involve youth contending with the juvenile justice system in a job readiness programme, Youth Kitchen, that interfaces the youth with farmers, chef educators, community organisations, and farmers markets. This paper contends that integrating alternative food and juvenile justice work is a complex terrain that both advances social justice and reproduces existing power asymmetries within alternative food networks. The inclusion of accounts from multiple stakeholders in the local food and juvenile justice system generates a multilayered view that moves away from an either sustainability or social justice rubric to a more process-oriented lens that reveals the strategic dilemmas that alternative food networks encounter. On the one hand, the social landscape of this programme promotes an ethic of care and shared ownership between the staff and participating youth. At the same time, akin to many alternative food networks, neoliberal interests bump against this ethic of care and white privilege seeps into staffing patterns and everyday programmes in ways that reproduce the status quo.     

成渝城市群碳排放空间关联结构演化及影响因素

本文基于社会网络分析法（SNA）以及二次分配程序（QAP）方法,利用成渝城市群2005~2016年面板数据,对成渝城市群碳排放空间关联性及影响因素进行研究.结果表明：①成渝城市群碳排放空间关联性显著,呈现出复杂的网络结构形态,样本期内,网络密度由0.16增长至0.68,关联关系数从38个增长为162个.②重庆、成都、绵阳和南充等城市位于网络的中心地位,发出了较多的关联关系,同时发挥着中介作用.③碳排放空间关联网络被划分成为5个层级,层级结构整体较为稳定,然而第一层级与第二层级存在较为严重的断层现象.④空间距离、人口数量差异以及经济水平差异是碳排放关联性的主要驱动因素.城市间空间距离越近、人口数量与经济水平差异越大,越容易产生碳排放关联关系.     

变电站大气环境腐蚀参数自动检测仪研制及应用

目的通过自主研发的大气环境腐蚀参数自动检测仪,监测并积累变电站大气腐蚀数据,判断大气腐蚀性,为变电站选择腐蚀与防护手段,提供数据支持和依据。方法依据变电站大气腐蚀研究的最新理论成果,参考最新国家标准,将影响变电站腐蚀因素的各参数整合,选择国内外最先进的传感器,根据实际工况要求,研制了一台基于变电站环境的大气腐蚀参数检测仪。结果仪器的各项技术指标均达到设计要求,能够满足现场要求,可以根据变电站设备材质要求,定制腐蚀传感器。结论通过在国家大气腐蚀网站(沈阳站)、浙江电力公司所属变电站的测试,研制的大气环境腐蚀参数自动检测仪能够实时采集影响腐蚀的各影响因子的参数值,满足未来腐蚀监测仪器、装备多参数、智能化的要求。