scholarly journals Prototype of a controllable damper based on granular materials subjected to partial vacuum

2019 ◽  
Vol 254 ◽  
pp. 05009
Author(s):  
Robert Zalewski ◽  
Piotr Bartkowski
Keyword(s):  
Energy Dissipation ◽  
Granular Materials ◽  
Atmospheric Pressure ◽  
Experimental Results ◽  
Friction Forces ◽  
The Core ◽  
The Difference ◽  
Partial Vacuum

In the paper a proposal of granular damper prototype has been introduced. The granular damper works on the basis of a core made of Vacuum Packed Particles. Idea of Vacuum Packed Particles consists of placing loose granular grains into a hermetic envelope, wherein in the next stage a partial vacuum is generated. The difference between an atmospheric pressure, externally surrounding the core and internal one, causes occurring friction forces between single grains. Interacting friction forces are greater for higher values of internal underpressure. In presented paper the authors focus on analysis of experimental results obtained for various values of underpressure. Variations in energy dissipation possibilities are particularly described in this paper.

Effects of Molecularly Thin Liquid Lubricant Film Materials on Slider Hysteresis Instability in Hard Disk Drives

2007 ◽  
Author(s):  
Norio Tagawa ◽  
Daisuke Tanaka ◽  
Atsunobu Mori
Keyword(s):  
Hard Disk Drives ◽  
Disk Surface ◽  
Intermolecular Forces ◽  
Experimental Results ◽  
Disk Drives ◽  
Friction Forces ◽  
Liquid Lubricant ◽  
Pressure Test ◽  
Lower Mobility ◽  
The Difference

In this study, the difference in the touchdown and takeoff pressures was monitored by using three types of lubricant materials, namely, Zdol2000, Ztetraol2000 and A20H2000 by using the pump down pressure test. The results indicated that the touchdown pressures depended on the lubricant materials; it was greatest for Ztetraol2000 and smallest for A20H2000. The takeoff pressure was greater for a lubricant with lower mobility. Considering these experimental results, it was suggested that the variation in the touchdown pressure is due to a variation in the intermolecular forces, taking into account the lubricant pickup by a slider. Further, it was suggested that the variation in the takeoff pressure is caused by a variation in the friction forces between the slider and disk surface.

A Study on the Application of Hybrid Panels to Ship Structures

2014 ◽  
Author(s):  
Takao Yoshikawa ◽  
Yukichi Takaoka ◽  
Masahiro Maeda
Keyword(s):  
Residual Deformation ◽  
Peel Strength ◽  
Experimental Results ◽  
Liquefied Petroleum Gas ◽  
Three Point Bending ◽  
The Core ◽  
Stiffened Structures ◽  
Weak Points ◽  
The Difference ◽  
Collapse Behavior

The application of hybrid panels composed of polyurethane foam cores and steel faceplates to hull structures was studied. First, the strength and collapse behavior of the panels were examined using three-point bending tests for hybrid panels with different core densities. Based on the experimental results, low-density core materials, such as those having a density of 300 kg/m3, are recommended for hybrid panels with respect to strength and weight. The structural strength of hybrid panels was investigated through a series of calculations utilizing FEA for beams clamped at both ends under uniform pressure by changing the thickness of the faceplates and core, and the length of the clamped span. Taking account of the structural advantages of hybrid panel structures, two kinds of applications for hybrid panels are proposed. One is in the inner bottom structure of bulk carriers. There is the possibility of improving the residual strength of hybrid panels after they are subjected to severe impacts. The dynamic characteristics of hybrid panels were investigated. It was confirmed that the residual deformation of hybrid structures after impact loading is less than that of ordinary stiffened structures of the same weight. The other application is in the structural members of pressurized LPG (Liquefied Petroleum Gas) tanks. In utilizing hybrid panels in LPG tanks, the difference in rigidity between the core and skin produces a high peak bending stress in the vicinity of the clamped ends. In this paper, measures for the mitigation of this phenomenon are proposed. Also, the difference in rigidity between core and skin also produces weak points in hybrid panels such as the interface between the core and skin-plate. The applicability of hybrid panels in tank systems was examined by numerical methods utilizing the experimental results and it was confirmed that the shear and peel strength of the interface is more than sufficient.

Spatial Social Choice

2019 ◽  
pp. 207-244
Author(s):  
Norman Schofield
Keyword(s):  
United States ◽  
Stochastic Model ◽  
Social Choice ◽  
Spatial Models ◽  
The United States ◽  
Multinomial Logit ◽  
Experimental Results ◽  
The Core ◽  
Voting Game ◽  
Voter Choice

A key concept of social choice is the idea of the Condorcet point or core. For example, consider a voting game with four participants so any three will win. If voters have Euclidean preferences, then the point at the center will be unbeaten. Earlier spatial models of social choice focused on deterministic voter choice. However, it is clear that voter choice is intrinsically stochastic. This chapter employs a stochastic model based on multinomial logit to examine whether parties in electoral competition tend to converge toward the electoral center or respond to activist pressure to adopt more polarized policies. The chapter discusses experimental results of the idea of the core explores empirical analyses of elections in Israel and the United States.

scholarly journals Experimental/Numerical Evaluation of Steel Trapezoidal Corrugated Infill Panels with an Opening

2021 ◽  
Vol 11 (7) ◽  
pp. 3275
Author(s):  
Majid Yaseri Gilvaee ◽  
Massood Mofid
Keyword(s):  
Energy Dissipation ◽  
Ultimate Strength ◽  
Steel Plate ◽  
Shear Walls ◽  
Experimental Results ◽  
Structural Performance ◽  
Initial Stiffness ◽  
Infill Panels ◽  
Energy Dissipation Capacity ◽  
Ductility Ratio

This paper investigates the influence of an opening in the infill steel plate on the behavior of steel trapezoidal corrugated infill panels. Two specimens of steel trapezoidal corrugated shear walls were constructed and tested under cyclic loading. One specimen had a single rectangular opening, while the other one had two rectangular openings. In addition, the percentage of opening in both specimens was 18%. The initial stiffness, ultimate strength, ductility ratio and energy dissipation capacity of the two tested specimens are compared to a specimen without opening. The experimental results indicate that the existence of an opening has the greatest effect on the initial stiffness of the corrugated steel infill panels. In addition, the experimental results reveal that the structural performance of the specimen with two openings is improved in some areas compared to the specimen with one opening. To that end, the energy dissipation capacity of the specimen with two openings is obtained larger than the specimen with one opening. Furthermore, a number of numerical analyses were performed. The numerical results show that with increasing the thickness of the infill plate or using stiffeners around the opening, the ultimate strength of a corrugated steel infill panel with an opening can be equal to or even more than the ultimate strength of that panel without an opening.

A Novel Locality Sensitive K-Means Clustering Algorithm based on Core Clusters

2013 ◽  
Vol 321-324 ◽  
pp. 1939-1942
Author(s):  
Lei Gu
Keyword(s):  
Clustering Algorithm ◽  
Experimental Results ◽  
Clustering Method ◽  
Neighborhood Graph ◽  
The Core ◽  
Random Samples

The locality sensitive k-means clustering method has been presented recently. Although this approach can improve the clustering accuracies, it often gains the unstable clustering results because some random samples are employed for the initial centers. In this paper, an initialization method based on the core clusters is used for the locality sensitive k-means clustering. The core clusters can be formed by constructing the σ-neighborhood graph and their centers are regarded as the initial centers of the locality sensitive k-means clustering. To investigate the effectiveness of our approach, several experiments are done on three datasets. Experimental results show that our proposed method can improve the clustering performance compared to the previous locality sensitive k-means clustering.

Comparing the Seismic Performance of Beam-Column Joints with and without SFRC when Subjected to Cyclic Loading

2012 ◽  
Vol 626 ◽  
pp. 85-89 ◽  
Author(s):  
Kay Dora Abdul Ghani ◽  
Nor Hayati Hamid
Keyword(s):  
Energy Dissipation ◽  
Cyclic Loading ◽  
Seismic Performance ◽  
Experimental Work ◽  
Concrete Beam ◽  
Steel Fiber ◽  
Precast Concrete ◽  
Experimental Results ◽  
Column Joint ◽  
Initial Cracks

The experimental work on two full-scale precast concrete beam-column corner joints with corbels was carried out and their seismic performance was examined. The first specimen was constructed without steel fiber, while second specimen was constructed by mixed up steel fiber with concrete and placed it at the corbels area. The specimen were tested under reversible lateral cyclic loading up to ±1.5% drift. The experimental results showed that for the first specimen, the cracks start to occur at +0.5% drifts with spalling of concrete and major cracks were observed at corbel while for the second specimen, the initial cracks were observed at +0.75% with no damage at corbel. In this study, it can be concluded that precast beam-column joint without steel fiber has better ductility and stiffness than precast beam-column joint with steel fiber. However, precast beam-column joint with steel fiber has better energy dissipation and fewer cracks at corbel as compared to precast beam-column joint without steel fiber.

scholarly journals Elemental composition and clustering behaviour of α-pinene oxidation products for different oxidation conditions

2015 ◽  
Vol 15 (8) ◽  
pp. 4145-4159 ◽  
Author(s):  
A. P. Praplan ◽  
S. Schobesberger ◽  
F. Bianchi ◽  
M. P. Rissanen ◽  
M. Ehn ◽  
...  
Keyword(s):  
Elemental Composition ◽  
Organic Compounds ◽  
Atmospheric Pressure ◽  
Molar Mass ◽  
Oxidation Products ◽  
Neutral Species ◽  
Mass Spectrometers ◽  
Comprehensive Picture ◽  
The Difference ◽  
Chemical Ionisation

Abstract. This study presents the difference between oxidised organic compounds formed by α-pinene oxidation under various conditions in the CLOUD environmental chamber: (1) pure ozonolysis (in the presence of hydrogen as hydroxyl radical (OH) scavenger) and (2) OH oxidation (initiated by nitrous acid (HONO) photolysis by ultraviolet light) in the absence of ozone. We discuss results from three Atmospheric Pressure interface Time-of-Flight (APi-TOF) mass spectrometers measuring simultaneously the composition of naturally charged as well as neutral species (via chemical ionisation with nitrate). Natural chemical ionisation takes place in the CLOUD chamber and organic oxidised compounds form clusters with nitrate, bisulfate, bisulfate/sulfuric acid clusters, ammonium, and dimethylaminium, or get protonated. The results from this study show that this process is selective for various oxidised organic compounds with low molar mass and ions, so that in order to obtain a comprehensive picture of the elemental composition of oxidation products and their clustering behaviour, several instruments must be used. We compare oxidation products containing 10 and 20 carbon atoms and show that highly oxidised organic compounds are formed in the early stages of the oxidation.

Simulation and experimentation of a magnetorheological brake with adjustable gap

2016 ◽  
Vol 28 (12) ◽  
pp. 1614-1626 ◽  
Author(s):  
Wan-Li Song ◽  
Dong-Heng Li ◽  
Yan Tao ◽  
Na Wang ◽  
Shi-Chao Xiu
Keyword(s):  
Magnetorheological Fluid ◽  
Structure Design ◽  
Experimental Results ◽  
Wear Property ◽  
Braking Performance ◽  
Braking Torque ◽  
The Difference ◽  
The Impact ◽  
Theoretical Analyses ◽  
Magnetostatic Simulation

The aim of this work is to investigate the effect of the small magnetorheological fluid gap on the braking performance of the magnetorheological brake. In this article, theoretical analyses of the output torque are given first, and then the operating principle and design details of the magnetorheological brake whose magnetorheological fluid gap can be altered are presented and discussed. Next, the magnetic circuit of the proposed magnetorheological brake is conducted and further followed by a magnetostatic simulation of the magnetorheological brakes with different sizes of fluid gap. A prototype of the magnetorheological brake is fabricated and a series of tests are carried out to evaluate the braking performance and torque stability, as well as the verification of the simulation results. Experimental results show that the braking torque increases with the increase in the current, and the difference for the impact of the fluid gap on braking performance is huge under different currents. The rules, which the experimental results show, have an important significance on both the improvement of structure design for magnetorheological brake and the investigation of the wear property under different fluid gaps.

Spatial Convergence in Height in Central Europe, 1890-1910

2009 ◽  
pp. 90
Author(s):  
Marek Brabec ◽  
John Komlos
Keyword(s):  
Global Economy ◽  
Well Being ◽  
Habsburg Monarchy ◽  
The Core ◽  
Military Recruits ◽  
Convergence Clubs ◽  
Spatial Convergence ◽  
Physical Stature ◽  
The Difference ◽  
Peripheral Areas

We examine spatial convergence in biological well-being in the Habsburg Monarchy, circa 1890-1910, on the basis of evidence of the physical stature of 21-year-old military recruits, disaggregated into 15 Districts. We find that the shorter the population in 1890, the faster its height grew thereafter. Hence, there was convergence in physical stature between the peripheral areas of the monarchy (located in today’s Poland/Ukraine, Romania, and Slovakia) and its core (located in today’s Austria, Czech Republic, and Hungary). The difference in trends between the trend in height in the Polish District of Przemysl and in Vienna was about 0.9 cm per decade, in favor of the former. Convergence among the core Districts themselves was minimal or non-existent, whereas the convergence among the peripheral Districts was more pronounced. Spatial convergence also took place between the peripheral regions and the more developed ones. The pattern is somewhat reminiscent of modern findings on convergence clubs in the global economy.

Gebruiksaspecten van het uitroeppartikel wat in het Nederlands en Fries

2020 ◽  
Vol 136 (4) ◽  
pp. 189-209
Author(s):  
Henk Wolf
Keyword(s):  
The Core ◽  
The Difference ◽  
Lexical Phrase ◽  
High Degree ◽  
Lexical Phrases

Abstract Both Dutch and (West) Frisian make use of the exclamative particle wat (‘how’), that adds an element of surprise about a high degree of something to the semantics of the sentence. In this paper I will first show the similarities between the use of the particle in the two languages. I will demonstrate that, in Dutch, its use is largely confined to constructions that are semantically scalable, whereas in Frisian this restriction is far less strict. I will explain the difference by showing that Dutch wat is a syntactic amplifier of lexical phrases, whereas Frisian wat has developed into a pragmatic amplifier of the core predicate. I will try to account for that difference by showing how homophonous words absent in Dutch are likely to have influenced the use of Frisian wat, and how Dutch prosody strengthens the connection between wat and the amplified lexical phrase, whereas Frisian prosody weakens it. Finally, I will show that the system described as ‘Frisian’ is occasionally found in varieties of Dutch too

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