A Method for Calculating Grounding Resistance of Reinforced Concrete Foundation Grounding Systems

The effect of nanopores geometry on desalination of single-layer graphene-based membranes: A molecular dynamics study

Physiologic dead space is usually estimated by the Bohr-Enghoff equation or the Fletcher method. Alveolar dead space is calculated as the difference between anatomical dead space estimated by the Fowler equal area method and physiologic dead space. This study introduces a graphical method that uses similar principles for measuring and displaying anatomical, physiologic, and alveolar dead spaces. A new graphical equal area method for estimating physiologic dead space is derived. Physiologic dead spaces of 1,200 carbon dioxide expirograms obtained from 10 ventilated patients were calculated by the Bohr-Enghoff equation, the Fletcher area method, and the new graphical equal area method and were compared by Bland-Altman analysis. Dead space was varied by varying tidal volume, end-expiratory pressure, inspiratory-to-expiratory ratio, and inspiratory hold in each patient. The new graphical equal area method for calculating physiologic dead space is shown analytically to be identical to the Bohr-Enghoff calculation. The mean difference (limits of agreement) between the physiologic dead spaces calculated by the new equal area method and Bohr-Enghoff equation was -0.07 ml (-1.27 to 1.13 ml). The mean difference between new equal area method and the Fletcher area method was -0.09 ml (-1.52 to 1.34 ml). The authors' equal area method for calculating, displaying, and visualizing physiologic dead space is easy to understand and yields the same results as the classic Bohr-Enghoff equation and Fletcher area method. All three dead spaces--physiologic, anatomical, and alveolar--together with their relations to expired volume, can be displayed conveniently on the x-axis of a carbon dioxide expirogram.

A simple and easy method to quantify the cool island intensity of urban greenspace

Modification of four point method to measure the concrete electrical resistivity in presence of reinforcing bars

Improved transient stability of virtual synchronous generators for grid voltage cascading faults

Carbon fiber reinforced polymer （CFRP） has the advantages of low weight， high tensile strength， corrosion resistance， and fatigue resistance， which makes it suitable for cable domes. To study the feasibility of applying CFRP cables in cable dome structures， some steel cables and single-type cables in an open cable dome structure with a span of 120 meters were replaced with CFRP cables using different methods. The static performance finite element analysis of the cable dome structure after the replacement of CFRP cables was carried out. The simulation results showed that， compared with the cable dome using steel cables， when some steel cables were replaced with CFRP cables by the equal area method， the stress of the cables in the replaced cable dome structure was reduced， and the stress of each group of cables was reduced by less than 8%. The maximum vertical displacement of the joints varied within 10%. When all single-type cables were replaced with CFRP cables by the equal strength method， the stress of the cables and the maximum vertical displacement of the joints changed significantly. Replacing all single-type cables with CFRP cables by the equal stiffness method had a relatively small impact on the stress of the cables and the maximum vertical displacement of the joints. For this open cable dome structure， all steel ridge cables can be replaced with CFRP cables. This research demonstrates that through reasonable design， it is feasible to use CFRP cables to replace steel cables in such structures.

Large deflection behavior of circular sandwich plates with metal foam-core

Big pole pitches of high-speed Permanent Magnet Linear Synchronous Motors (PMLSMs) cause many problems. Permanent Magnet (PM) width modulation secondary is an excellent solution to these problems, and conducive to the suppression of thrust ripple. This paper studies two design approaches of this novel secondary: equal area method and triangular modulation method. Firstly, the modeling of PM width modulation secondary for high-speed PMLSM is studied, the schemes of equal area method and triangular modulation method are presented. Furthermore, thrust features of PMLSMs with PM width modulation secondary, based on the two methods respectively, are analyzed and compared. A prototype is manufactured to verify the feasibility of PM width modulation secondary. The results provide base data of PM width modulation secondary for highspeed PMLSM.

The transient tability of the general 2-machine system is considered in this paper. Introduction of an equivalent system with concentrated inertia at one end is shown to facilitate the direct application of the equal area method of analysis to the general 2-machine system. Heretofore the equal area method has been confined to certain special 2-machine systems.

Using buffer analysis to determine urban park cooling intensity: Five estimation methods for Nanjing, China

Steel pallet rack (SPR) beam-to-column connections (BCCs) are largely responsible to avoid the sway failure of frames in the down-aisle direction. The overall geometry of beam end connectors commercially used in SPR BCCs is different and does not allow a generalized analytic approach for all types of beam end connectors; however, identifying the effects of the configuration, profile and sizes of the connection components could be the suitable approach for the practical design engineers in order to predict the generalized behavior of any SPR BCC. This paper describes the experimental behavior of SPR BCCs tested using a double cantilever test set-up. Eight sets of specimens were identified based on the variation in column thickness, beam depth and number of tabs in the beam end connector in order to investigate the most influential factors affecting the connection performance. Four tests were repeatedly performed for each set to bring uniformity to the results taking the total number of tests to thirty-two. The moment-rotation (M-θ) behavior, load-strain relationship, major failure modes and the influence of selected parameters on connection performance were investigated. A comparative study to calculate the connection stiffness was carried out using the initial stiffness method, the slope to half-ultimate moment method and the equal area method. In order to find out the more appropriate method, the mean stiffness of all the tested connections and the variance in values of mean stiffness according to all three methods were calculated. The calculation of connection stiffness by means of the initial stiffness method is considered to overestimate the values when compared to the other two methods. The equal area method provided more consistent values of stiffness and lowest variance in the data set as compared to the other two methods.

The transient tability of the general 2-machine system is considered in this paper. Introduction of an equivalent system with concentrated inertia at one end is shown to facilitate the direct application of the equal area method of analysis to the general 2-machine system. Heretofore the equal area method has been confined to certain special 2-machine systems.

A cyclic quadrilateral is called a Brahmagupta quadrilateral if the lengths of its four sides and two diagonals, and the area are all given by integers. In this paper, we consider the hitherto unsolved problem of finding two Brahmagupta quadrilaterals with equal perimeters and equal areas. We obtain two parametric solutions of the problem — the first solution generates examples in which each quadrilateral has two equal sides while the second solution gives quadrilaterals all of whose sides are unequal. We also show how more parametric solutions of the problem may be obtained.

PurposeThe purpose of this paper is to investigate the performance of Passive Direct Methanol Fuel Cell (PDMFC) experimentally using various Membrane Electrode Assembly (MEA) shapes such as square, rectangle, rhombus, and circle with equal areas and equal perimeters. The variation in MEA shape/size is achieved by altering gasket openings in the dynamic regions.Design/methodology/approachIn the equal areas of MEA shapes, gasket opening areas of 1963.5 (+/−0.2) mm2 are used. Whereas in the equal perimeters of shapes, gasket opening perimeters of 157.1 (+/−0.2) mm are used. In this experimentation, Nickel-201 current collectors with 45.3% of circular openings are used on both the anode and cathode sides. The experiment is carried out at a 5 molar methanol concentration to find out the highest power density of the cell.FindingsIn the equal areas, among the shapes that are chosen for investigation, the square shape opening consisting of a perimeter of 177.2 mm has developed a maximum power density of 6.344 mWcm−2 and a maximum current density of 65.2 mAcm−2. Similarly, in equal perimeters, the rhombus shape opening with an area of 1400 mm2 has developed a maximum power density of 7.714 mWcm−2 and a maximum current density of 85.3 mAcm−2.Originality/valueThe novelty of this research work is instead of fabricating various shapes and sizes of highly expensive MEAs, the desired shapes and sizes of the MEA are achieved by altering gasket openings over dynamic regions to find out the highest power density of the cell.

Much has been written on triangles having areas and perimeters of equal numerical value. Markowitz (1981) determined that only five triangles having sides with integral lengths exist for which the areas equal the perimeters, but that infinitely many have rational side lengths. (Throughout this article, when it is stated that triangles have equal area and perimeter, it means that they are numerically equal.) Markowitz (1981) and Bates (1979) both determine equations satisfied by triangles having equal areas and perimeters, but these equations can only be used through trial and error. The purpose of this article is to find a method that will easily generate any number of triangles of equal area and perimeter, and also geometrically characterize such triangles.