Open-Air Quarries in the Urban Commune of Zinder (South-East Niger): An Opportunity with Strong Externalities

The framing of this theme would contribute to a better analysis of the benefits of open-air quarrying in Zinder, and should make it possible to understand and measure the socio-environmental externalities of this type of activity in an urban environment. The approach method consisted of carrying out surveys combined with field observations and interviews with the various stakeholders as well as the local population. The results obtained made it possible to identify both positive and negative impacts. The positive impacts are above all the advantages derived from these aggregate quarries, in particular, the creation of direct and permanent jobs and the increase in community income. The price of piling up a truck costs around 28,000 CFA ($56 CAN) and that of loading is around 10,000 F CFA ($20 CAN). This has the effect of removing young people (20 - 39 years old) from the circuit of migration outside the region and even the country. The possibility of using the extraction sites by the local population was identified, in terms of profits relating to fish farming, off-season crops, animal drinking and reclaimed plots. The study also noted negative externalities, such as the temptation of young boys to become involved in extractive activities for immediate gains at the expense of school attendance. Added to this is the upheaval in the topography of the urban landscape, pollution and nuisances (noise, visual and olfactory), while the disappearance or clogging of quarry ponds is the cause of frequent flooding in the neighborhoods. In short, corrective measures (e.g. the revegetation of sites) certainly make it possible to minimize the harmful impacts on the urban environment. But, to improve the performance and organizational capacity of the quarrying industry in Niger, even stronger regulation, training and awareness of stakeholders prove to be the necessary measures.

Language of Open-Air Market in North-Central Nigeria

Language plays a significant role in business,trade and commerce.Bargaining in open-air markets often involves the speech act of negotiating,compromising and manoeuvring,which could either result in conflict or persuasion of the potential buyer to patronize a seller.This article examined the sociolinguistic aspects of language use between sellers and buyers in Ipata,a popular market in Ilorin,north-central Nigeria.The call strategy,spiel,honorification,pragmatic mechanics as well as sociolinguistic style employed by vendors were observed.The objectives of the study were to:identify the number of languages used in Ipata market;investigate the factors that influence the choice of any of the languages used between sellers and buyers at a particular time;analyze their sociolinguistic and stylistic features;and discuss some of the barriers that could cause intercultural communication breakdown between sellers and buyers in a market situation.Oral interview,systematic observation and Bauman’s(2001)method of street recording were used to gather data for the study.Sixty-five people comprising thirty-six females and twenty-nine males were interviewed.The survey which spanned three months discovered that open-air markets bear some universal features,however,due to cultural relativity,variations occur.To this end,it was established that Ipata market harbours different languages;it also identified calls and spiels with their characteristic stylistic,sociolinguistic and discourse features in the market.In conclusion,the study argued that studying the verbal discourse of marketplaces is significant as it defines what the language-culture-society-relationship is all about.

Phase separation and domain crystallinity control enable open-air-printable highly efficient and sustainable organic photovoltaics

Organic solar cells(OSCs)have emerged as a promising solution for sustainable energy production,offering advantages such as a low carbon footprint,short energy payback period,and compatibility with eco-solvents.However,the use of hazardous solvents continues to dominate the best-performing OSCs,mainly because of the challenges of controlling phase separation and domain crystallinity in eco-solvents.In this study,we combined the solvent vapor treatment of CS2 and thermal annealing to precisely control the phase separation and domain crystallinity in PM6:M-Cl and PM6:O-Cl systems processed with the eco-solvent o-xylene.This method resulted in a maximum power conversion efficiency(PCE)of 18.4%,which is among the highest values reported for sustainable binary OSCs.Furthermore,the fabrication techniques were transferred from spin coating in a nitrogen environment to blade printing in ambient air,retaining a PCE of 16.0%,showing its potential for high-throughput and scalable production.In addition,a comparative analysis of OSCs processed with hazardous and green solvents was conducted to reveal the differences in phase aggregation.This work not only underscores the significance of sustainability in OSCs but also lays the groundwork for unlocking the full potential of open-air-printable sustainable OSCs for commercialization.

Comparison of bone artifacts from the Schöningen site in Germany and the Lingjing site in China

Similarities play an important role in the reconstruction of human physical,cultural and technological evolution.The two sites presented in this paper,the Middle Palaeolithic site Lingjing in China Layer 10 and 11 and the Lower Palaeolithic site Schöningen 13Ⅱ-4,the socalled Schöningen Spear Horizon in Germany,show striking similarities.The archaeological record of both sites includes lithic artifacts as well as a very large assemblage of fossil bones.The preservation of the material at both sites is excellent and the faunas encountered at both sites show many similarities.The faunal lists of both sites include a diverse carnivore guild,an elephant species,two different rhinoceros species,two different equids,different cervids and large bovids.Both sites also yielded bone retouchers as well as a unique record of bone hammers that show identical,unusual flaking and percussion damage.These similarities are remarkable if one takes into account the difference in age(ca 200 kaBP)and the geographical distance between the two sites of ca 8000 km.Therefore,we do not assume a close cultural link between the hominin populations active at both sites.The authors assume that the observed similarities show more or less identical,opportunistic hominin behaviour at both sites located in a comparable environment with more or less similar taphonomic conditions.

Thermo-Physical Potential of Recycled Banana Fibers for Improving the Thermal and Mechanical Properties of Biosourced Gypsum-Based Materials

The development of bio-sourced materials is essential to ensuring sustainable construction;it is considered a locomotive of the green economy.Furthermore,it is an abundant material in our country,to which very little attention is being given.This work aims to valorize the waste of the trunks of banana trees to be used in construction.Firstly,the physicochemical properties of the fiber,such as the percentage of crystallization and its morphology,have been determined by X-ray diffraction tests and scanning electron microscopy to confirm the potential and the impact of the mode of drying on the quality of the banana fibers,with the purpose to promote the use of this material in construction.Secondly,the results obtained with the gypsum matrix allowed us to note a preponderant improvement in the composite’s thermal properties thanks to the variation of the banana fiber additive.Thirdly,the impact of the nature of the banana fiber distribution(either fiber mixed in matrix or fiber series model)on the flexural and compressive strengths of the composites was studied.The results obtained indicate that the insulation gain reaches up to 40%.It depends on the volume fraction and type of distribution of the banana fibers.However,the thermal inertia of the composites developed,represented by thermal diffusivity and thermal effusivity,was studied.Results indicate a gain of 40%and 25%,respectively,in terms of thermal diffusivity and thermal effusivity of the developed composites compared to plaster alone.Concerning the mechanical properties,the flexural strength depends on the percentage of the volume fraction of banana fibers used,and it can reach 20%more than the flexural strength of plaster;nevertheless,there is a significant loss in terms of the compressive strength of the studied composites.The results obtained are confirmed by the microstructure of the fiber banana.In fact,the morphology of the banana fibers was improved by the drying process.It reduces the amorphous area and improves the cellulosic crystalline surfaces,which assures good adhesion between the fiber and the matrix plaster.Finally,the dimensionless coefficient analysis was done to judge the optimal proportion of the banana fiber additive and to recommend its use even on false ceilings or walls.

传感器位置对大型冷库库内温度及风机运行规律的影响

目前,冷库多通过库内布置传感器所采集的温度信号控制冷风机启停,进而维持适宜贮存温度。为探索不同位置传感器对大型冷库库内温度及风机运行时长的影响,本文以一实际使用的大型冷库为为原型构建计算模型,模拟研究了不同传感器位置导致风机运行规律变化,进而引起冷库温度波动情况。结果表明,“冷库升温”过程中,传感器布置在侧墙中部响应效果最佳;“关门降温”过程,传感器平行侧墙布置在冷库中部时,所导致的风机能耗最小;“开门降温”过程,传感器平行布置在冷库中间可以实现风机最佳的响应时间。

侧面爆破粉尘时空分布模拟分析

从开放性细颗粒物污染治理角度出发,建立建筑物拆除爆破产尘的几何计算模型,运用计算流体力学(CFD)工具,对给定环境风速下的建筑物周围压力场和速度场进行了模拟分析,并对侧面折叠爆破粉尘按R-R(Rosin-Rammler)分布,使用气流-粒子双向耦合的DPM模型研究了爆炸粉尘的时空分布。结果表明,下风侧因建筑物存在导致风速、压力急剧变化而产生涡流,涡流是影响爆破粉尘时空分布的关键因素之一。在时间上,爆破粉尘有气流拖曳运动状态和扩散态;在空间上,因重力作用致下部空间的粉尘浓度较大。

高铁开通对中国航空客运网络连通性的影响

为了科学优化中国航空客运网络发展,选取2000—2018年中国定期通航的运输机场所在地级及以上城市的非平衡面板数据,将高铁开通视为一项准自然实验,采用多期双重差分模型实证分析高铁开通对中国航空客运网络连通性水平的影响。研究发现:高铁开通显著提升了中国航空客运网络连通性水平;高铁开通对节点中心性的提升作用不受该城市所处区域的影响,均有显著的促进作用,对东部城市中心性的促进作用大于中西部城市。

定向送风对隔离病房开门时段空气泄漏的抑制效果研究

患有高传染性疾病的患者一般被安置在医院的负压隔离病房中来限制这些疾病在医院内部的传播。然而隔离病人员进出时房门开启可能会导致大量携带有病菌的空气通过房门传递到隔离病房外部走廊,从而引起走廊中的人员被感染。为了减少和预防门开启带来的室内空气泄露问题,有必要使得门开启时室内外交换的气流最小化。为了解决这个问题,我们在隔离病房门口安装有定向气流送风口,通过将定向气流引向隔离病房门口,以减少由门的开启过程,人员移动通过过程和室内外温差引起的室内外空气气流交换量。使用烟雾对流场可视化后发现在门开启或者关闭的过程中使用朝向隔离病房的定向气流能够明显减小室内外的空气交换量。示踪气体测试结果显示,定向气流90L/s时室内外等温条件下可将隔离病房内的空气泄漏量减少38%,而室内外温差3℃时,使用定向气流可减小泄漏量31%。若将定向气流风量调节到190L/s时,等温条件下可减小室内外60%的空气交换量。在室内外存在3℃的温差时,空气交换量可减少39%。尽管测试的定向气流并未能够完全防止空气泄漏,但是它们是可以有效的减少由门的开启,人员通过和室内外温差引起的室内外空气交换量。

开式空气循环热泵干燥系统性能仿真分析

为解决能源使用效率低、HCFC/HFC等非环保制冷剂使用等问题,提出了不同于传统干燥技术的以空气为工质的空气循环热泵干燥(ACHPD)系统新技术。建立了数学仿真模型,通过所构建实验台的实验结果进行验证,干燥速率误差在±0.01%以内,系统功率误差在±7%以内。与传统的电加热器干燥(EHD)系统相比,当水质量蒸发率从0.75 kg/h增至3.45 kg/h时,ACHPD系统的节能率达到15%~27%。进气温度由10℃增至40℃和相对湿度由30%增至80%分别使单位除湿能效比(MER)降低约7%和21%。膨胀机效率由0.55增至0.8和压缩机效率由0.4增至0.9会使系统的能效分别降低17%和36%。

基于无人机摄影和点云配准的建筑露天深基坑变形视觉监测方法

基坑顶部位移、地表沉降以及管线变形监测误差较大,影响建筑露天深基坑施工质量。为了减小建筑露天深基坑变形监测误差,本文设计一种基于无人机摄影和点云配准的建筑露天深基坑变形视觉监测方法。规划无人机飞行范围和航飞步骤,设置每次航飞参数以及航向和旁向重叠率,完成无人机摄影图像数据采集;建立露天深基坑变形监测模型,设计监测模型流程,基于点云配准实现变形监测;利用监测模型计算误差参数和两组同名点间坐标转换关系,得到校正坐标;进行点云之间的配准,实现变形视觉监测。利用工程实例对设计的监测方法进行性能测试,结果表明,在某工程的基坑顶部位移、地表沉降以及管线变形监测测试中,本文设计的监测方法与实际情况更接近,误差有效减小。

大型露天建筑绿色施工扬尘污染治理方法研究

扬尘对人体和周边环境都具有很大的危害。为实现绿色施工,进行扬尘污染治理是十分必要的,因此研究一种大型露天建筑绿色施工扬尘污染治理方法。该研究从白果中提取纤维素并制备成纳米纤维素,再制成纳米纤维素抑尘剂。将纳米纤维素抑尘剂喷洒到地面,固化后实现扬尘污染治理。根据是否喷洒抑尘剂,设置实验组和对照度,实施吸湿保水性能测试和风蚀性能测试,结果表明:实验组吸湿强度更高、保水率更大,土样质量损失率、TSP浓度更大,说明纳米纤维素抑尘剂喷洒能够保持土样湿润性,增强了土样的抗风蚀性能,起到了扬尘污染治理的效果。

航空发动机露天试车台测试计量校准研究

利用ANSYS workbench静力学分析模块对航空发动机露天试车台的计量校准问题进行了探讨。首先,仿真计算了航空发动机露天试车台在不同载荷下的形变,与试验数据进行对比验证计算结果的准确性;其次,基于ASHRAE模型计算了太阳辐射强度。利用ANSYS热分析模块对太阳辐射引起的试车台结构温度变化进行了分析;最后,利用模态模块研究了露天试车台在阳光照射下的动力学特性变化规律。结果表明,静态分析模拟和试验的平均误差小于15.29%。试车台的固有频率受温度影响变化较小,当试车台的温差为50 K时,六阶固有频率可降低0.03 Hz。这些结果对推动航空发动机露天试车台试验参数标定具有重要价值。

基于极限平衡法的某露天采场边坡稳定性分析研究

边坡稳定性直接关系到露天矿山的安全开采,为分析露天矿采场边坡稳定性,本文以西藏某露天铜矿采场高陡边坡为研究对象,根据矿山边坡现状、边坡岩体结构和结构面发育特征等因素对现状边坡进行地质分区,通过岩石室内物理力学试验获得坡体岩石物理力学参数,利用两种不同的极限平衡法方法计算各分区在3种荷载工况下现状边坡稳定性系数。计算结果显示,该各地质分区现状边坡所有荷载组合下的安全系数均满足规范要求,可为矿山安全生产提供参考。

某露天煤矿钢波纹管涵应用可行性研究

为解决某露天煤矿剥离运输系统与运煤运输系统的交叉问题,以B立交工程位置为研究对象,选取适于该露天矿运输现状的立交工程方法,基于现场调研,以定量与定性结合方式确定了钢波纹管方案。为进一步提升露天矿的经济效益与开采效率,提出了3组钢波纹管方案,选取最适于该露天煤矿的钢波纹管优化方案。

深凹立面建筑房间自然通风效果及污染物浓度分布

以西安地区某主导风向为侧向来风的深凹立面建筑房间为研究对象,通过过渡场模型对室外场到室内场进行了多尺度CFD模拟,研究了不同开窗方式下的室内空气质量。结果显示:全开窗对于排出室内产生的污染物有较好效果,但是对于室外污染物的抵抗能力不如单开平立面窗;当室内污染物集中于某个单个房间时,开窗形成的对流通风会造成其他无污染源房间内的污染物浓度增大;当污染物分散在各个房间时,对流通风则可以有效降低各房间污染物浓度,降低幅度约为50%;单开平立面窗能有效杜绝室外污染物进入室内,而增大出风口是排出室内污染物的最好方法。

垂直单向流洁净室下夹层空气流速与孔板排布规律研究

提出了基于高架地板下夹层空气流速的量纲一速度参数K_(1),利用ANSYS Fluent软件对不同洁净室结构形式、风机过滤单元布置率和出口风速等条件下的空态洁净室高架地板布置方式与下夹层空气流速的匹配关系进行了研究。结果表明:当K_(1)<5时,洁净室内宜使用相同规格开孔率的孔板均匀布置;当5≤K_(1)<9时,应优先使用具有一定压力梯度变化的孔板非均匀布置,其次使用低开孔率的孔板均匀布置;当K_(1)≥9时,应使用具有较大压力梯度的孔板非均匀布置,且K_(1)值越大,靠近回风道位置孔板开孔率越小,孔板压力梯度变化越大。

露天石灰岩矿山高陡岩质边坡治理

因不规范开采形成的高陡边坡,易引发滑坡、坍塌等地质灾害,给矿山安全稳定带来极大影响。文章以溧阳某采石灰岩矿山为例,分析了该矿山地质环境条件,探讨了高陡岩质边坡整治及生态修复策略,希望可以为类似边坡治理提供借鉴。

电子雷管在露天矿山中的降振应用及分析

为研究露天矿山开采过程中,导爆管雷管与电子雷管起爆网络对爆破振动的影响规律,通过在相同采区控制一次起爆药量相同,分别使用导爆管雷管和电子雷管进行起爆,同时在距离爆区400m、450m、500m分别设置爆破振动监测点,对两种起爆方式下的振频率、最大振速和振动能量分布进行了分析。结果显示:相对于导爆管雷管起爆网络,采用电子雷管起爆最大振速降低20.5%,平均降振率13.9%;主振频率由最高8.761Hz增加至15.267Hz;通过MATLAB对爆破振动信号进行分析得到,使用电子雷管进行起爆时,其振动能量最大降低44%,平均能量降低29.8%,降振效果显著。

基于空间谱估计技术测向系统的开场测试

本文利用相关干涉仪体制无线电监测测向系统的测试验证技术基础,通过分析基于空间谱估计技术的无线电测向系统的开场测试参数及方法,设计了针对空间谱测向系统特性的开场测试场地,完善了监测设施测试验证的技术手段。