A comprehensive investigation of loading variance influence on fuel consumption and gas emissions in mine haulage operation

The data collected from haul truck payload management systems at various surface mines show that the payload variance is significant and must be considered in analysing the mine productivity, diesel energy consumption, greenhouse gas emissions and associated costs. The aim of this study is to determine the energy and cost saving opportunities for truck haulage operations associated with the payload variance in surface mines. The results indicate that there is a non-linear relationship between the payload variance and the fuel consumption, greenhouse gas emissions and associated costs. A correlation model, which is independent of haul road conditions, has been developed between the payload variance and the cost saving using the data from an Australian surface coal mine. The results of analysis for this particular mine show that a significant saving of fuel and greenhouse gas emissions costs is possible if the standard deviation of payload is reduced from the maximum to minimum value.

Strength of circular concrete columns under concentric compression

An experimental study, in which six columns were loaded concentrically toinvestigate the behavior of reinforced normal strength and high strength circular columns underconcentric compression, is described. The concrete strengths of the columns were 30 MPa and 60 MPa.The primary variables considered were the concrete strength and the amount of transversereinforcement. Test results indicate that smaller hoop spacing provides higher column capacity andgreater strength enhancement in a confined concrete core of columns. For the same lateralconfinement, high strength concrete columns develop lower strength enhancement than normal strengthconcrete columns. Both the strength enhancement ratio (f'_(cc) /f'_(co)) and the column capacityratio (P_(test)/P_o) were observed to show linear increase variations with rho_s f_(yt)/f'_c incircular columns.

Unified strength model based on the Hoek-Brown failure criterion for fibre-reinforced polymer-confined pre-damaged concrete columns with circular and square cross sections

Fibre-reinforced polymer(FRP)has the advantages of high strength,light weight,corrosion resistance and convenient construction and is widely used in repairing and strengthening damaged concrete columns.Most of the existing strength models were built by regression analysis of experimental data;however,in this article,a new unified strength model is proposed using the Hoek-Brown failure criterion.To study the strength of FRP-confined damaged and undamaged concrete columns,900 test data were collected from the published literature and a large database that contains the cross-sectional shape of each specimen,the damage type,the damage level and the FRP-confined stiffness was established.A new strength model using the Hoek-Brown failure criterion was established and is suitable for both circular and square columns that are undamaged,load-damaged and fire-damaged.Based on the database,most of the existing strength models from the published literature and the model proposed in this paper were evaluated.The evaluation shows that the proposed model can predict the compressive strength for FRP-confined pre-damaged and undamaged concrete columns with good accuracy.

Bi-level hybrid local search approach for three-dimensional loading problem with balancing constraints

This paper presents a bi-level hybrid local search(BHLS)algorithm for the three-dimensional loading problem with balancing constraints(3DLP-B),where several rectangular boxes with even densities but different sizes are loaded into a single cubic bin to meet the requirements of the space or capacity utilization and the balance of the center of gravity.The proposed algorithm hybridizes a novel framed-layout procedure in which the concept of the core block and its generation strategy are introduced.Once the block-loading sequence has been determined,we can load one block at a time by the designed construction heuristic.Then,the double-search is introduced;its external search procedure generates a list of compact packing patterns while its internal search procedure is used to search the core-block frames and their best distribution locations.The approach is extensively tested on weakly to strongly heterogeneous benchmark data.The results show that it has better performance in improving space utilization rate and balanced condition of the placement than existed techniques:the overall averages from 79.85%to 86.45%were obtained for the balanced cases and relatively high space-usage rate of 89.44%was achieved for the unbalanced ones.

Energy-Aware Scheduling Scheme Using Workload-Aware Consolidation Technique in Cloud Data Centres

To reduce energy consumption in cloud data centres,in this paper,we propose two algorithms called the Energy-aware Scheduling algorithm using Workload-aware Consolidation Technique(ESWCT) and the Energyaware Live Migration algorithm using Workload-aware Consolidation Technique(ELMWCT).As opposed to traditional energy-aware scheduling algorithms,which often focus on only one-dimensional resource,the two algorithms are based on the fact that multiple resources(such as CPU,memory and network bandwidth)are shared by users concurrently in cloud data centres and heterogeneous workloads have different resource consumption characteristics.Both algorithms investigate the problem of consolidating heterogeneous workloads.They try to execute all Virtual Machines(VMs) with the minimum amount of Physical Machines(PMs),and then power off unused physical servers to reduce power consumption.Simulation results show that both algorithms efficiently utilise the resources in cloud data centres,and the multidimensional resources have good balanced utilizations,which demonstrate their promising energy saving capability.

Unified bearing capacity model of confined concrete column subjected to axial compression

To better study the behavior of confined concrete, this paper presents the basic hypothesis of uhimate equilibrium of confined concrete and the unified yield criteria of confining material. Based on the static equilibrium condition and yield criteria of components, a unified bearing capacity model of confined concrete column is proposed, and a simplified calculating equation of the model is also given. The model captures the character of confined concrete column. Effects of the confinement effect ratio, the lateral confinement ratio, unconfined concrete strength and the properties of confining material on the bearing capacity of confined concrete column are carefully considered. The model may be applicable to the calculation of bearing capacity of steel-confined concrete, concrete filled steel tube and FRP-confined concrete. The predictions of the model agree well with test data.

Undrained Behaviour of Silt under Static and Cyclic Loading

In this study, the undrained behaviour of silt under low stress level is studied. An effective preparation method for built-in silt samples in the triaxial test was firstly developed. By triaxial testing of samples at low confining pressures it was found that silt easily loses stability and liquefies. Loose silt may show temporary liquefaction under static loading, and develop full liquefaction under cyclic loading. The most important factors influencing the silt behaviour are porosity, confining pressure, consolidation state, cyclic loading level and number of cycles. The maximum obtainable shear stress is primarily a function of the confining pressure and the internal frictional angle. The actual structure of the silt material is the key factor in controlling its behaviour.

Membrane action in lateral restraint reinforced concrete slabs

Based on the assumption of additional three-hinge arching action,an analytical method was proposed to predict the additional load of lateral restraint reinforced concrete (RC) slab under compressive membrane action (CMA),and its ultimate load could be obtained by adding pure bending load. The experiment of twelve one-way RC slabs supported by shear-walls was carried out,and the calculations of this proposed method provide good predictions for the experimental evidences. The influence of some design parameters on bearing capacity was also investigated. It is shown that the effect of vertical load on ending shear-wall on the ultimate load capacity can be generally neglected when the bending restraint is satisfied. The additional load capacity also decreases with the increase of the span-to-height ratio of central slab. When reducing the reinforcement area,the additional load capacity is increased,and this method can be used to save steel or enhance the ultimate load capacity of low steel ratio slab.

Load Balancing in WDM Optical Networks with and without Wavelength-Continuity Constraints

In practical optical networks, there is often the same number of wavelengths in a fiber. But if it is not carefully designed, there will be much difference in link load among different fibers, and unnecessary wavelengths will be needed. This paper investigated this load balancing issues to minimize the wavelength requirements. Both Integer Linear Programming (ILP) and heuristic algorithms were presented to solve such a problem in WDM optical networks with or without wavelength continuity constraints.

Bearing capacity of concrete filled bidirectional FRP tube subjected to axial compression

External confinement by fiber reinforced polymer (FRP) is an efficient technique to increase the bearing capacity and ductility of concrete. To better study the mechanical behavior of bidirectional FRP confined concrete, the yield criterion of bidirectional FRP is presented based on the static equilibrium condition in this paper, and a model for calculating the bearing capacity of bidirectional FRP confined concrete is established. The model can capture the character of bidirectional FRP confined concrete. Effects of the confinement effect coefficient, the unconfined concrete strength and the material properties of FRP on bearing capacity are analyzed. Results show that each parameter has different effects on the bearing capacity of bidirectional FRP confined concrete.

《蒼頡篇》“發傳約載”補論

《蒼頡篇》'發傳約載'中,'發傳''約載'均爲動賓結構,前者訓作發送傳車,後者指置辦傳車,該句文意與秦漢傳遽律令有關。

Regional Differentiation and Classification for Carrying Constraints on the Resources and Environment of China

Research on the relationship between national resource constraint-region types and environmental carrying capacity is essential for the continued development of Chinese industrialization and urbanization.Thus,utilizing a series of key indexes including the per-capita potential of available land resources,the per-capita potential of available water resources,the degree of environmental stress,and the degree of ecological restriction,a step-by-step,integrated measuring method is presented here to understand the constrained carrying elements of water and land resources as well as environment and ecology.Spatial differences are analyzed and area types classified at the county level across China.Results reveal that：（1）Almost 90%of China is strongly constrained by both resources and the environment,while nearly 50%of national territory is strongly constrained by two elements,especially in areas of intensive population and industry to the east of the Helan-Longmen Mountain line;（2）Densely populated areas of eastern and central China,as well as on the Tibetan Plateau,are strongly constrained by a shortage of land resources,while North China,the northwest,northeast,the Sichuan basin,and some southern cities are experiencing strong constraints because of water shortages.In contrast,the North China plain,the Yangtze River delta,northern Jiangsu,Sichuan province,Chongqing municipality,Guizhou and Guangxi provinces,the northeast plain,and the northern Loess Plateau are constrained by high levels of environmental stress.Areas of China that are strongly ecologically constrained tend to be concentrated to the southwest of the Tianshan-Dabie Mountain line,as well as in the northeast on the Loess Plateau,in the Alashan of Inner Mongolia,in northeast China,and in the northern Jiangsu coastal area;（3）Constraints on national resources and environmental carrying capacity are diverse and cross-cut China,meanwhile,multi-element spatial distribution does reveal a degree of relative centralization.With the exception of the Tibetan Plateau which is resources-ecological constraint,other areas subject to cross constraints are mainly concentrated to the east of the Helan-Longmen Mountain line.