There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

计量经济分析 = Econometric analysis

This chapter discusses leading problems linked to energy that the world is now confronting and to propose some ideas concerning possible solutions. Oil deserves special attention among all energy sources. Since the beginning of 1981, it has merely been continuing and enhancing the downward movement in consumption and prices caused by excessive rises, especially for light crudes such as those from Africa, and the slowing down of worldwide economic growth. Densely-populated oil-producing countries need to produce to live, to pay for their food and their equipment. If the economic growth of the industrialized countries were to be 4%, even if investment in the rational use of energy were pushed to the limit and the development of nonpetroleum energy sources were also pursued actively, it would be extremely difficult to prevent a sharp rise in prices. It is evident that it is absolutely necessary to pursue actively the development of coal, natural gas, and nuclear power if a physical shortage of energy is not to block economic growth.

World energy outlook

Introduction to stochastic programming

Modern electrical power system is evolving to a smarter and agile system, which will support society's sustainable development. The low voltage grid should be capable of withstanding new challenges such as reverse power flows and voltage unbalance (VU) caused by distributed generation. In this paper, the mitigation possibilities of the VU caused by single-phase-connected photovoltaics (PV) are analysed with Tesla Powerwall 2 battery energy storage systems (BESS) added to the grid. Three different BESS phase connection strategies are modelled and the VU is assessed with Monte Carlo Simulation (MCS). A low voltage distribution grid in Sweden is considered with different PV and BESS penetration levels and the applied method for VU assessment is validated. Simulation results reveal the effectiveness of VU mitigation by connecting PV and BESS to the same phase.

/pdf/stochastic-assessment-of-voltage-unbalance-mitigation-by-4a2rztkcc4.pdf

Stochastic Assessment of Voltage Unbalance Mitigation by Home Battery System in Low Voltage Grid with Single-Phase Solar Power Generation

In this paper, novel and efficient analytical closed-form expressions are proposed for the optimal allocation of multiple capacitors in distribution systems to maximize the total cost reduction (CR) while considering power losses. The proposed expressions are novel since they can directly solve the allocation problem without requiring iterative processes or optimization algorithms. Specifically, two analytical closed-form expressions are introduced to determine the optimal number, locations, and sizes of multiple capacitors. The first analytical expression computes directly the optimal sizes of multiple capacitors where it is employed for the optimal sizing of capacitors for all possible combinations of locations. In turn, the best combination is then assigned by using a second analytical expression which directly evaluates all the combinations in terms of their contribution in CR. Unlike the existing methods/expressions that utilize sensitivity factors or optimize each capacitor individually, the proposed analytical closed-form expressions involve a unified mathematical model for multiple capacitors. The proposed direct approach is tested using a 69-bus distribution system. The accuracy and efficacy of the proposed analytical closed-form expressions are verified by comparisons with existing methods and intensive simulations of various allocation scenarios.

/pdf/direct-approach-for-optimal-allocation-of-multiple-8z83q7ws30.pdf

Direct approach for optimal allocation of multiple capacitors in distribution systems using novel analytical closed-form expressions

This paper examines dynamics of escalator energy consumption in different passenger volumes with a simulation model of an existing escalator pair installation. The model segregates the energy consumption into components by operation mode and carried passenger mass. The simulation results emphasize the energy consumption of an intermittent escalator to depend highly on the passenger traffic volume. Changes in volume affect the share of energy consumption components and achievable savings by energy efficient features. In low traffic, equipped energy saving features drastically reduce energy consumption. Findings of this paper are applicable as supportive material in the selection process of escalators to assure cost-efficient and high-energy performance escalator systems.

Modelling the daily energy consumption of escalators with various passenger volumes

https://file.scirp.org/pdf/ENG_2014102808580326.pdf

Design, Implementation and Simulation of Non-Intrusive Sensor for On-Line Condition Monitoring of MV Electrical Components

Parallel developments in electric vehicles' battery technologies and the charging equipment is leading the transportation and logistics sector towards a new era. This paper focusses on the quick charging needs of passenger electric vehicles for their optimal charging in terms of total charging time and network capacity utilization. Power distribution network capacity is utilized in such a way that, charging power to each of the individual charging socket is assigned based on the state of charge of the connected electric vehicle to that particular charging socket. An algorithm has been designed to intelligently allocate the charging power to the individual sockets at the fast charging station to control the charging rate of electric vehicles. Each of the connected electric vehicle could be charged to a certain level of state of charge depending on the length of the queue to avoid congestion of the queue and give chance to other electric vehicles to begin their charging. Simulation results show the relation between available network capacity, number of charging sockets at the charging station and the queuing time of EVs.

Matti Lehtonen

Papers

Stochastic Assessment of Voltage Unbalance Mitigation by Home Battery System in Low Voltage Grid with Single-Phase Solar Power Generation

Direct approach for optimal allocation of multiple capacitors in distribution systems using novel analytical closed-form expressions

Modelling the daily energy consumption of escalators with various passenger volumes

Design, Implementation and Simulation of Non-Intrusive Sensor for On-Line Condition Monitoring of MV Electrical Components

Minimization of queuing time of electric vehicles at a fast charging station