Wood Density Determination with the Perspective to Decarbonisation of Tropical Forest Species from the Luki Biosphere Reserve in the Democratic Republic of the Congo

Specimens of the forest species such as Pentaclethra macrophylla, Petersianthus macrocarpus, Pycnanthus angolensis and Terminalia superba have been sampled from LUKI Biosphere reserve in the Democratic Republic of the Congo in order to determine their wood density with the perspective to decarbonisation. These parameters have been found out experimentally utilizing a drying technique in an oven including techniques of immersion in an Erlenmeyer full of water. The corresponding results indicated that the four species wood density is respectively 0.85, 0.80, 0.77 and 0.51. These preliminary results will be useful in our ongoing project on carbon dioxide absorption capacity of Congo rainforest tree species.

MnO_4^-和银含量对铅银合金阳极电位衰减期电化学行为的影响(英文)

研究在电位衰变期间在酸性硫酸锌电解液中,MnO4-和银的含量对5个通用铅银合金阳极电化学行为的影响。当阳极浸入不含MnO4-的酸性硫酸锌电解液中时,通过开路电位测定,发现Pb-0.72%Ag进入完全钝化状态所用的时间最短,紧接着的是阳极Pb-0.67%Ag、Pb-0.60%Ag、Pb-0.58%Ag和Pb-0.29%Ag-0.1%Ca。在5h的浸入期间,MnO4-离子能加速钝化和增加阳极的腐蚀电流密度。通过交流阻抗法测定,发现在含有MnO4的电解液中,阳极Pb-0.72%Ag具有最好的耐蚀性,紧接着的是阳极Pb-0.67%Ag、Pb-0.60%Ag,然后是阳极Pb-0.58%Ag和Pb-0.29%Ag-0.1%Ca。

网状和片状氧化涂层阳极在电解锌过程中的电化学行为（英文）

研究两个网状和一个片状氧化涂层阳极在38°C的电解锌溶液中的催化性能,并与通用的Pd-0.7%Al合金的电化学性能进行对比。采用电化学测试方法进行实验,如循环动电位法、恒电流法、动电位法、开路电位法和原位电化学噪音法。经过2 h的开路电位实验,线性极化结果表明:网状Ti/(IrO_2-Ta_2O_5)电极显示出非常好的性能,其腐蚀电流密度在三个氧化涂层阳极中是最低的(3.37μA/cm^2)。此外,在50 m A/cm2和38°C的条件下,经过24 h的恒电流极化试验,网状Ti/MnO_2阳极有最高的电位(1.799 V),紧随其后的是片状Ti/(IrO_2-Ta_2O_5)(1.775V)和网状Ti/(IrO_2-Ta_2O_5)阳极(1.705 V)。经过24 h的恒电流极化和16 h时的电位衰退实验后,线性极化方法验证了经过2 h的开路电位实验得出的结果,即网状Ti/(IrO_2-Ta_2O_5)阳极有最低的腐蚀电流。网状Ti/(IrO_2-Ta_2O_5)阳极在24 h极化后显示出更好的性能,并与通用的Pb-0.7%Al合金进行相比,过电位低~245 mV。

Determining relative block structure rating for rock erodibility evaluation in the case of non-orthogonal joint sets

The most commonly used method for assessing the hydraulic erodibility of rock is Annandale's method.This method is based on a correlation between the erosive force of flowing water and the capacity of rock resistance. This capacity is evaluated using Kirsten's index, which was initially developed to evaluate the excavatability of earth materials. For rocky material, this index is determined according to certain geomechanical factors related to intact rock and rock mass, such as compressive strength of intact rock, rock block size, discontinuity shear strength and relative block structure. To quantify the relative block structure, Kirsten(1982) developed a mathematical expression that accounts for the shape and orientation of the blocks relative to the direction of flow. Kirsten's initial concept for assessing the relative block structure considers that the geological formation is mainly fractured by two joint sets forming an orthogonally fractured system. An adjusted concept is proposed to determine the relative block structure when the fractured system is non-orthogonal where the angle between the planes of the two joint sets is greater or less than 90°. An analysis of the proposed relative block structure rating shows that considering a non-orthogonally fractured system has a significant effect on Kirsten's index and, as a consequence, on the assessment of the hydraulic erodibility of rock.

Organization：A new focus on mine safety improvement in a complex operational and business environment

The daily operations in the mining industry are still a significant source of risk with regard to occupational safety and health(OS & H). Various research studies and statistical data world-wide show that the number of serious injuries and fatalities still remains high despite substantial efforts the industry has put in recent years in decreasing those numbers. This paper argues that the next level of safety performance will have to consider a transition from coping solely with workplace dangers, to a more systemic model taking organizational risks in consideration. In this aspect, lessons learned from the nuclear industry may be useful, as organizational learning processes are believed to be more universal than the technologies in which they are used. With the notable exception of major accidents, organizational performance has not received all the attention it deserves. A key element for reaching the next level of performance is to include organizational factors in low level events analyses, and approach the management as a risk control system. These factors will then appear not only in the event analysis,but in supervision activities, audits, change management and the like. Many recent event analyses across various industries have shown that organizational factors play a key role in creating conditions for triggering major accidents(aviation, railway transportation, nuclear industry, oil exploitation, mining, etc.).In this paper, a perspective that may be used in supervisory activities, self-assessments and minor events investigations, is presented. When ingrained in an organizational culture, such perspective has the highest potential for continuous safety improvement.

加拿大魁北克水电站项目中结晶岩的水压致裂试验

自1997年以来,在加拿大地盾进行了250多次水压致裂试验,该试验是魁北克不同的水电站项目调查选址的一部分,所有项目都位于格伦维尔和超级地质省,那里的基岩由结晶质火成岩和变质岩组成。水压致裂试验是为了确定在水压条件下岩体渗透率的增加,进而定义隧洞衬砌承载的上限。对不同试验结果的研究表明,在深度小于150m时,大规模结晶岩的岩体性质相似。我们给出了来自闭合曲线和P-Q曲线图的最小应力统计数据的分析,并与投入使用的压力隧洞的渗漏相比较。所采用的解释方法也在最小主应力求解中扮演着关键角色。所以破裂和破裂重张压力的比值在分析结果中是一个重要的参数。

沿冰层表面流注传播场稳定性的实验研究与分析(英文)

The electric field required for stable propagation of a positive streamer along an ice surface was investigated by measuring the currents associated with the streamer discharge.The influence of the surface properties,namely the existence of a water film on the ice surface and surface contamination,was analyzed.Results showed that in the presence of an ice surface,except in case of low conductive surface,streamers propagate stably with an external field lower than that generally measured for propagation in air alone(approximately 5 kV/cm).For higher contamination levels,the stability field was found to be slightly influenced by the temperature,while for lower contamination levels,it decreased significantly with an increase in temperature.

Micro-Modelling Approach to Predict the Influence of Hydrogen Pressure on Short Crack Behaviour

A micromechanical model, based on the FEA (finite element analysis), was developed to estimate the influence of hydrogen pressure on short crack behaviour. Morphology of voids has important connotations in the development of the model. Stress intensity factor was calculated for different crack geometries under hydrogen pressure. The analysis indicates that the form factor of a crack emerging from a round void will be less affected by trapped hydrogen pressure-compared to an elongated void. This analysis reinforces the beneficial effect of inclusion shape control in reducing significantly the detrimental effect of hydrogen.

Calculation of the Stress Intensity Factor in an Inclusion-Containing Matrix

The intent of this paper is to propose an engineering approach to estimate the stress intensity factor of a micro crack emerging from an inclusion in relation with the morphology of the inclusion and its relative stiffness with the matrix. A micromechanical model, based on the FEA (finite element analysis) of the behavior of cracks initiated at micro structural features such as inclusions, has been developed using LEFM (Linear Elastic Fracture Mechanics) to predict the stress intensity factor of a micro crack emerging from an inclusion. Morphology of inclusions has important connotations in the development of the analysis. Stress intensity factor has been estimated from the FEA model for different crack geometries. Metallographic analysis of inclusions has been carried out to evaluate the typical inclusion geometry. It also suggests that micro cracks less than 1?μm behave differently than larger cracks.

Improved deterministic reserve allocation method for multi-area unit scheduling and dispatch under wind uncertainty

This paper presents a security constrained unit commitment(SCUC)suitable for power systems with a large share of wind energy.The deterministic spinning reserve requirement is supplemented by an adjustable fraction of the expected shortfall from the supply of wind electric generators(WEGs),computed using the stochastic feature of wind and loosely represented in the security constraint with scenarios.The optimization tool commits and dispatches generating units while simultaneously determining the geographical procurement of the required spinning reserve as well as load-following ramping reserve,by mixed integer quadratic programming(MIQP).Case studies are used to investigate various effects of grid integration on reducing the overall operation costs associated with more wind power in the system.

Numerical Simulation of Wake-Field Acceleration Using an Eulerian Vlasov Code

We study the generation of nonlinear plasma wake fields by intense laser pulses,using an Eulerian code for the numerical solution of the fully relativistic onedimensional(1D)Vlasov-Maxwell equations.The examination of the phase-space of the distribution function allows to study without numerical noise aspects of the particle acceleration by the wake-field generated by intense laser pulses,in the very low density regions of the phase-space.We study the effect of the thermal spread on the existence of accelerated beams,and we compare between results obtained from a circularly polarized wave and a linearly polarized wave.