Optimization of Urban Rail Transportation in Emerging Countries Using Operational Research Techniques

Rail systems are gradually becoming the most desirable form of transit infrastructure around the world, partly because they are becoming more environmentally friendly compared with airplanes and automobiles. This paper examines the place of emerging countries in this move of implementing modern rail system that will eventually enhance the realization of a low-carbon society. Network model, transportation model and linear programming algorithms are used to model the present urban rail transport system in Nigeria, as an emerging country, in order to optimize it. Operational research methods, including simplex method and MODI, with the aids of computer software (excel solver and LIP solver) were adopted to solve the resulting models. The results showed that optimization of rail transport system will not only reduce carbon emission but also bring about economic development which is required for the eradication of prevalent poverty in these emerging countries.

Power and Cross-Spectra for the Turbulent Atmospheric Motion and Transports in the Domain of Wave Number Frequency Space: Theoretical Aspects

The study of large-scale atmospheric turbulence and transport processes is of vital importance in the general circulation of the atmosphere. The governing equations of the power and cross-spectra for the atmospheric motion and transports in the domain of wave number frequency space have been derived. The contributions of the nonlinear interactions of the atmospheric waves in velocity and temperature fields to the conversion of kinetic and potential energies and to the meridional transports of angular momentum and sensible heat in the atmosphere have been discussed.

Obstacles Facing Developing Countries in Power System Planning

The problem of power system planning, due to its complexity and dimensionality, is one of the most challenging problems facing the electric power industry in developing as well as developed countries. In planning phase, two of the most important decision-making parameters are the reliability and costs. The latter includes both system investment costs and outages costs. In this paper, these parameters are described and the interrelation between them is evaluated. Some previous approaches and developed techniques will he applied to a particular planning problem in a developing country and some aspects having a significant impact on the decision making process in the planning phase will be considered.

Preliminary Analysis of Special Tourism Transportation in Agricultural Eco-scenic Area

Transport varies greatly in agricultural eco-scenic areas for the diversity of resources, and different terrains such as mountains, low hills and forest lands. Special tourism transportation is common in scenic area of different themes. For agricultural eco-scenic area, the road design has to consider the theme of the scenic area, thus animal power is a favorable transportation choice, it refl ects agricultural ecological characteristics and also takes production needs into consideration. This paper analyzed road design characteristics of agricultural eco-scenic area, and proposed the transportation model dominated by animal power and considering farming production, so as to meet the standards of "rural road" in agricultural eco-scenic area and comply with the style of agricultural tourism, and satisfy the visitors.

The Challenges Faced on Transit Transport Corridors by Landlocked Countries in Central Africa: Literature Review

The landlocked countries are the one without access to the sea and can be assimilate as countries around the world with a disadvantage of geography situation location. Chad and the Central African Republic are two of the 40 landlocked countries around the world that transport 80% of their goods by road and rail, and as much as almost more than 50% of their passengers through a transit country with a transit transport system which is crucial for their trade and exchanges. The study aims to introduce the importance to have a good and efficiency transport network infrastructure in Central Africa to facilitate the trade for the landlocked countries of Central Africa (Chad and the Central African Republic), member of CEMAC trade area and proposes some measures that can be adopted to improve their conditions and ameliorate the trade for those countries.

Prospects for Channel Construction of Sending Power from Westto East in the Next 10 Years

This paper describes the planned power transmission from west to east through three channels. It presents the main characteristics of these three channels and the problems need to be solved.

Review of current progress in hole-transporting materials for perovskite solar cells

Recent advancements in perovskites’ application as a solar energy harvester have been astonishing. The power conversion efficiency(PCE) of perovskite solar cells(PSCs) is currently reaching parity(>25 percent), an accomplishment attained over past decades. PSCs are seen as perovskites sandwiched between an electron transporting material(ETM) and a hole transporting material(HTM). As a primary component of PSCs, HTM has been shown to have a considerable effect on solar energy harvesting, carrier extraction and transport, crystallization of perovskite, stability, and price. In PSCs, it is still necessary to use a HTM.While perovskites are capable of conducting holes, they are present in trace amounts, necessitating the use of an HTM layer for efficient charge extraction. In this review, we provide an understanding of the significant forms of HTM accessible(inorganic, polymeric and small molecule-based HTMs), to motivate further research and development of such materials. The identification of additional criteria suggests a significant challenge to high stability and affordability in PSC.

POWER REFLECTION AND TRANSMISSION IN BEAM STRUCTURES CONTAINING A SEMI-INFINITE CRACK

Wave reflection and transmission in a beam containing a semi-infinite crack are studied analytically based on Timoshenko beam theory., Two kinds of crack surface conditions： non-contact （open） and fully contact （closed） cracks, are considered respectively for an isotropic beam. The analytical solution of reflection and transmission coefficients for a semi-infinite crack is obtained. The power reflection and transmission ratios depend on both the frequency and the position of the crack. Numerical results show the conservation of power transport. The transmitted energy among various wave modes is also investigated. A finite element method is used to verify the validity of the analytical results.

Atmospheric Dispersion and Deposition of Radionuclides (¹³⁷Cs and ¹³¹I) Released from the Fukushima Dai-ichi Nuclear Power Plant

The Lagrangian Particle Dispersion Model (LPDM) in the 594 km× 594 km model domain with the horizontal grid scale of 3 km×3 km centered at a power plant and the Eulerian Transport Model (ETM) modified from the Asian Dust Aerosol Model 2 (ADAM2) in the domain of 70° LAT × 140° LON with the horizontal grid scale of 27 km×27 km have been developed. These models have been implemented to simulate the concentration and deposition of radionuclides (137Cs and 131I) released from the accident of the Fukushima Dai-ichi nuclear power plant. It is found that both models are able to simulate quite reasonably the observed concentrations of 137Cs and 131I near the power plant. However, the LPDM model is more useful for the estimation of concentration near the power plant site in details whereas the ETM model is good for the long-range transport processes of the radionuclide plume. The estimated maximum mean surface concentration, column integrated mean concentration and the total deposition (wet+dry) by LPDM for the period from 12 March to 30 April 2011 are, respectively found to be 2.975 × 102 Bq m-3, 3.7 × 107 Bq m-2, and 1.78 × 1014 Bq m-2 for 137Cs and 1.96 × 104 Bq m-3, 2.24 × 109 Bq m-2 and 5.96 × 1014 Bq m-2 for 131I. The radionuclide plumes released from the accident power plant are found to spread wide regions not only the whole model domain of downwind regions but the upwind regions of Russia, Mongolia, Korea, eastern China, Philippines and Vietnam within the analysis period.

Nonlinear Analysis of Bedload Transport Rate of Paroxysm Debris Flow

The evolution characteristics of bedload transport feature of paroxysm debris flow have been studied by means of both theory analysis and experimental data.The analysis based on the flume experiment data of a sand pile model as well as a large amount of field data of debris flow clearly shown that the statistical distribu- tion for the main variable of the sand pile made of non-uniform sand (according the sand pile experiment,φ≥2.55) conform to the negative power law,that means the non-uniform sand syste...

Intermodal Terminal Localisation Using a Linear Programming Approach: The Case Study of Togo and West African Landlocked Countries

In this paper, four potential cities to host an intermodal terminal for containers flowing through the Togolese transport corridor are examined. The transport cost minimization through the corridor is the main objective. Consequently, the transport modes that offer the least cost to the transport supply chain are proposed. To attain this goal the paper aims to identify the optimal location for an intermodal terminal on the Togolese corridor, by using the mathematical linear programming model. For this, three transport scenarios are analyzed, the rail, the road, and the combination of these two transport modes to each of the landlocked countries (LLCs) capital cities of Burkina Faso, Mali and Niger. Data of the average transport cost per mode, the cargo demand of the LLCs, and the distances from origin to destinations are input in the LINGO software. Based on the optimization results, we find that among the preselected terminals, the city of Mango located at 550 km in the northern part of the country is the optimal host location for an intermodal terminal along the Togolese corridor. The results of this study may be helpful to transport policy makers in the quest of rendering better servicing to the landlocked countries.

Unit stream power,minimum energy dissipation rate,and river engineering

Unit stream power is the most important and dominant parameter for the determination of transport rate of sand,gravel,and hyper-concentrated sediment with wash load.Minimum energy dissipation rate theory,or its simplified minimum unit stream power and minimum stream power theories,can provide engineers the needed theoretical basis for river morphology and river engineering studies.The Generalized Sediment Transport model for Alluvial River Simulation computer mode series have been developed based on the above theories.The computer model series have been successfully applied in many countries.Examples will be used to illustrate the applications of the computer models to solving a wide range of river morphology and river engineering problems.

The ASEAN experience of the purchasing power parity theory

We used panel data analysis to evaluate the relative purchasing power parity(PPP)hypothesis of the ten ASEAN member countries between 1973 and 2015.We incorporated the cross-sectionally augmented panel unit root test as proposed by Pesaran(J Appl Econ 22:265-312,2007).For panel cointegration analysis,we employed the four error-correction-based Westerlund(Oxf Bull Econ Stat 69:709-748,2007)panel cointegration tests.The Westerlund(Oxf Bull Econ Stat 69:709-748,2007)tests are general enough to permit a large degree of heterogeneity,both in the long-run cointegrating relationship and in the short-run dynamics,and dependence within as well as across the cross-sectional units.To check the robustness of the results,we further estimated the cointegration test excluding Indonesia and Brunei.The findings support our initial results.Further,all the results overwhelmingly support the relative PPP hypothesis.Consequently,the monetary authority would be able to implement a self-regulating monetary policy.It would also be able to control the exchange rates.

The Importance of the Generation of Emission Factors for Developing Countries： Case of Mexico

Developing countries as Mexico lack their own emission factors for thermoelectric power plants, so they have the need to develop them, considering specific operation conditions for each plant. This study develops specific emission factors in Mexico for： sulfur dioxide （SO2）, nitrogen oxides （NOx） and particles, for thermoelectric power plants that use fuel oil. This work was necessary due to the differences found between the measured and the calculated emissions, using emission factors of different agencies, such as, US-EPA （Environmental Protection Agency of the United States）, IPCC （Intergovernmental Panel on Climate Change）, and UK-NAEI （National Atmospheric Emissions Inventory of the United Kingdom）. The new emission factors were used to calculate the emissions of a thermoelectric power plant in Mexico. The comparisons between the measured and the calculated emissions （with the new emission factors） for 502, particles and NO2 were not significantly different （p 〉 0.05）.

Development and Research of Non⁃Stirring Conveying Device for Waste Resin in Nuclear Power Plant

Blockage in the storage and transportation of waste resin is a difficult problem in the radioactive waste treatment process of nuclear power plants.In this study,in order to solve the problems of unstable resin transport concentration and easy blockage of conveying equipment and pipelines in nuclear power plants in China,a set of non⁃stirring conveying devices is developed,and theoretical calculations,simulation analysis and experimental verification are carried out.By transporting resin using the no stirring conveying device developed in this paper,it is not only to eliminate the risk of blockage and ensure the safety of transportation,but also to adjust the concentration of conveying resin to change the transport efficiency according to the operating conditions.The effective bearing rate of waste resin storage tank can be improved,so that the comprehensive performance of waste resin storage and transportation in nuclear power plants can be greatly improved.

Titanylphthalocyanine as hole transporting material for perovskite solar cells

Titanylphthalocyanine （TiOPc） as hole transporting material （HTM） was successfully synthesized by a simple process with low cost. Perovskite solar cells using the TiOPc as HTM were fabricated and characterized. TiOPc as HTM plays an important role in increasing the power conversion efficiency （PCE） by minimizing recombi- nation losses at the perovskite/Au interface because TiOPc as HTM can extract photogenerated holes from the perovskite and then transport quickly these charges to the back metal electrode. In the research, the β-TiOPc gives a higher PCE than α-TiOPc for the devices due to sufficient transfer dynamics, The β-TiOPc was applied in perovskite solar cells without clopping to afford an impressive PCE of 5.05% under AM 1.5G illumination at the thickness of 40 nm which is competitive with spiro-OMeTAD at the same condition. The present work suggests a guideline for optimizing the photovoltaic properties ofperovskite solar cells using the TiOPc as the HTM.

Battery with Integrated Power Supply(BALIN)

The BALIN is a modern device,consisting of a battery with integrated battery charger,dedicated to powering the 24 V services of the carriages.In various Trenitalia rolling stock,used for the regional transport of travelers,there are old and obsolete battery charger devices and there are lead acid batteries that need frequent maintenance operations to be kept efficient.These components,due to their low reliability,are the source of serious disruptions to passenger transport,and the management of their maintenance involves high costs for Trenitalia.In order to solve these problems,Trenitalia has therefore decided to invest resources to develop a new system of integrated power supplies and batteries,therefore the BALIN has been developed.The main advantages of BALIN compared to the original components are the presence of a high energy efficiency battery charger designed to operate in a wide range of temperatures and the presence of sealed lead-acid batteries without maintenance with a life exceeding 6 years.The BALIN is able to disconnect its own batteries from the carriage electrical circuits.The BALIN battery charger also implements an intelligent battery management logic and thanks to the interface with the command and control signals present on the rolling stock,the batteries are isolated from the carriage electric load automatically when the train is off and the service it's over.Another important automatic feature of the BALIN is to protect its batteries from deep discharge,in fact the power supply from the batteries to the electric carriage loads is interrupted when the voltage reaches 21 V.The characteristics mentioned go towards the reduction of the charge/discharge cycles of batteries and contribute to increasing the reliability and durability of batteries throughout the entire life of the rolling stock.

水路交通系统的发展现状与未来展望

水路交通系统是以船舶等为载运工具、以港口为节点、以海洋、江河、湖泊等水域为通道的一种运输方式,能够实现货物、人员的搭载与时空位移,是综合交通体系中不可或缺的重要组成部分。本文分析了国内外水路交通系统发展现状,梳理了水路交通系统未来需求及技术特征,提出了水路交通运输规划与组织优化、绿色船舶动力系统及供给体系、人机共融船舶岸基驾控系统、海域立体综合运输系统、水路交通系统控制体系、气象导航与安全航行等未来水路交通系统发展方向,为提高水路交通系统运营效率与服务质量提供理论基础与技术参考。

教育强国的数字化特征、关键指标与发展路向

国家将教育数字化作为教育强国建设的重要内容进行专门部署,强调教育数字化是开辟教育发展新赛道和塑造教育发展新优势的重要突破口。为了明晰教育数字化对我国教育强国建设的深远意义和影响,以及推进教育数字化转型与创新的现实路径,文章首先通过文献研究梳理了世界教育强国教育数字化发展的共同特征,总结了我国教育数字化转型面临的问题与挑战。其次,通过引入“教育硬实力”和“教育软实力”的理论分析框架,从过程与状态的双重视角构建了衡量数字化发展的表现性关键指标,为教育数字化助力实现教育强国目标锚定了重点方向。最后,立足当前我国教育强国建设背景下数字化的发展进程与现实挑战,提出发展对策:打造世界一流的教育数字基座、形成中国特色的数字教育思想、构建影响世界的数字教育生态、完善数字教育公共服务体系、加强数字化全民终身学习体系与推动数字教育产业集群纵深发展。

教育强国背景下数字教育的内涵、特点、难点与进路

建设教育强国是以中国式现代化推进中华民族伟大复兴的基础工程。发展数字教育是教育强国建设的必由之路,也是破解教育事业改革发展瓶颈的重要抓手。我国推进数字教育具有独特性,既处于数字中国宏大的战略目标下,需要高标准快速推进,又面临庞大教育规模和多样化教育需求的挑战,必须谨慎前行。我国对教育的持续投入及技术的快速迭代为推进数字教育提供了不竭动力,但也应看到,在建设教育强国背景下,我国发展数字教育存在育人方式较为传统、办学模式偏向保守、管理体制有待完善和保障机制亟须健全等问题,因此,亟须通过变革育人方式、创新办学模式、改革管理体制、完善保障机制等措施,有效推进我国数字教育发展,为教育强国建设提供有力支撑。