scholarly journals Improved 2D model of a ball bearing for the simulation of vibrations due to faults during run-up

2011 ◽  
Vol 305 ◽  
pp. 012033 ◽  
Author(s):  
Matej Tadina ◽  
Miha Boltežar
Keyword(s):  
Ball Bearing ◽  
Run Up ◽  
2D Model

Ball bearing turbocharger vibration management: application on high speed balancer

2020 ◽  
Vol 21 (6) ◽  
pp. 619
Author(s):  
Kostandin Gjika ◽  
Antoine Costeux ◽  
Gerry LaRue ◽  
John Wilson
Keyword(s):  
Dynamic Behavior ◽  
High Speed ◽  
Internal Combustion Engines ◽  
Ball Bearing ◽  
Squeeze Film ◽  
Design And Technology ◽  
Squeeze Film Damper ◽  
Damping Coefficients ◽  
Bearing Loads ◽  
Stiffness And Damping

Today's modern internal combustion engines are increasingly focused on downsizing, high fuel efficiency and low emissions, which requires appropriate design and technology of turbocharger bearing systems. Automotive turbochargers operate faster and with strong engine excitation; vibration management is becoming a challenge and manufacturers are increasingly focusing on the design of low vibration and high-performance balancing technology. This paper discusses the synchronous vibration management of the ball bearing cartridge turbocharger on high-speed balancer and it is a continuation of papers [1–3]. In a first step, the synchronous rotordynamics behavior is identified. A prediction code is developed to calculate the static and dynamic performance of “ball bearing cartridge-squeeze film damper”. The dynamic behavior of balls is modeled by a spring with stiffness calculated from Tedric Harris formulas and the damping is considered null. The squeeze film damper model is derived from the Osborne Reynolds equation for incompressible and synchronous fluid loading; the stiffness and damping coefficients are calculated assuming that the bearing is infinitely short, and the oil film pressure is modeled as a cavitated π film model. The stiffness and damping coefficients are integrated on a rotordynamics code and the bearing loads are calculated by converging with the bearing eccentricity ratio. In a second step, a finite element structural dynamics model is built for the system “turbocharger housing-high speed balancer fixture” and validated by experimental frequency response functions. In the last step, the rotating dynamic bearing loads on the squeeze film damper are coupled with transfer functions and the vibration on the housings is predicted. The vibration response under single and multi-plane unbalances correlates very well with test data from turbocharger unbalance masters. The prediction model allows a thorough understanding of ball bearing turbocharger vibration on a high speed balancer, thus optimizing the dynamic behavior of the “turbocharger-high speed balancer” structural system for better rotordynamics performance identification and selection of the appropriate balancing process at the development stage of the turbocharger.

Wave Run-Up on a Simulated Beach

1977 ◽  
Author(s):  
A. J. Sutherland ◽  
J. N. Sharma ◽  
O.H. Shemdin
Keyword(s):  
Run Up

The Alliance between Fundamentalist Christians and the Pro-Israel Lobby: Christian Zionism in US Middle East Policy

2004 ◽  
Vol 2 (2) ◽  
pp. 163-187
Author(s):  
Donald E. Wagner
Keyword(s):  
Middle East ◽  
Political Influence ◽  
Conservative Movement ◽  
International Media ◽  
Christian Zionism ◽  
The Us ◽  
Run Up ◽  
Middle East Policy ◽  
Near Future ◽  
Political Scene

It is a common assumption in the international media that the fundamentalist Christian Right suddenly appeared on the US political scene following the 11 September 2001 tragedy, and that it became a major force in shaping US policy in the Middle East. While it is true that fundamentalist Christians have exercised considerable influence during the George W. Bush administration, their ascendance is neither new nor surprising. The movement has demonstrated political influence in the US and England intermittently for more than a hundred years, particularly in the formation of Middle East policy. This article focuses on the unique theology and historical development of Christian Zionism, noting its essential beliefs, its emergence in England during the nineteenth century, and how it grew to gain prominence in the US. The alliance of the pro-Israel lobby, the neo-conservative movement, and several Christian Zionist organizations in the US represents a formidable source of support for the more maximalist views of Israel's Likud Party. In the run-up to the 2004 US presidential elections this alliance could potentially thwart any progress on an Israeli–Palestinian peace plan in the near future. Moreover, Likud ideology is increasingly evident in US Middle East policy as a result of this alliance.

Skenario Tsunami Menggunakan Data Parameter Gempabumi Berdasarkan Kondisi Batimetri (Studi Kasus : Gempabumi Maluku 28 Januari 2004 )

Jurnal Segara ◽  
2015 ◽  
Vol 11 (2) ◽  
Author(s):  
Robby Wallansha ◽  
Wiko Setyonegoro
Keyword(s):  
Run Up

Maluku merupakan salah satu daerah di timur Indonesia yang memiliki potensi tsunami yang cukup tinggi, ini dibuktikan dengan lebih dari 25 kejadian tsunami yang terekam di daerah Maluku dari tahun 1629 – 2006 (katalog database tsunami online Gusiakov (2005), Puspito (2007) dan Katalog Gempa Merusak dan Tsunami BMKG), tsunami yang terbesar terjadi pada tanggal 17 Pebruari 1674 yang menewaskan lebih dari 2900 orang dengan run-up hingga mencapai 80 meter dan menghancurkan kota Ambon dan juga pada tanggal 12 Oktober 1899 yang menenggelamkan kota Amahai di Pulau Seram dengan korban tewas mencapai 4000 orang. Oleh karena itu perlu dilakukan pembuatan skenario tsunami untuk mendapatkan kemungkinan tinggi run-up yang bersumber di daerah perairan Maluku dengan menggunakan software Tsunami L-2008. Berdasarkan Katalog Gempabumi Signifikan dan Merusak 1821 – 2009 yang dikeluarkan BMKG, bahwa pada tanggal 28 Januari 2004 telah terjadi gempabumi di Maluku mengakibatkan tsunami yang terobservasi di Namlea, dengan epicenter 3,110 LS – 127,300 BT dengan kekuatan Mw = 6,6 SR. Dalam pembuatan skenario tsunami dalam penelitian ini dengan merubah nilai magnituda gempabumi (Mw=7,0 SR, Mw=7,5 SR. Mw=8,0 SR) berdasarkan referensi setelah itu menggunakan hubungan rumusan empiris dari Hanks and Kanamori untuk mendapatkan nilai slip (m) sekaligus membuat beberapa kombinasi skenario tsunamidengan mempertahankan nilai momen seismik dan merubah nilai luas fault dan slip (m), untuk momen seismik didapatkan berdasarkan rumusan empiris dari Wells and Coppersmith (1994) sedangkan untuk luas fault berdasarkan rumusan empiris dari  Papazachos et al (2004) dengan mengasumsikan bahwa luas fault berbentuk persegi panjang. Dari sebelas skenario tsunami yang dibuat dari setiap magnituda gempabumi diperoleh tinggi run-up tertinggi untuk Mw=7,0 SR yaitu dengan tinggi 0,59 m di daerah Huamual sedangkan terendah di daerah Latuhalat dengan tinggi run-up 0,09 m, untuk Mw = 7,5 SR diperoleh tinggi run-up tertinggi mencapai 2,73 m di Huamual dan terendah 0,36 di Latuhalat, dan untuk Mw = 8,0 SR didapatkan tinggi run-up tertinggi hingga 8,19 m di Huamual dan terendah di Latuhalat dengan tinggi run-up 0,94 m.

The Never-ending Story of Law and Electoral System in Lesotho

2018 ◽  
Vol 4 (1) ◽  
Author(s):  
Hoolo Nyane
Keyword(s):  
Political Parties ◽  
Prime Minister ◽  
Legal Discourse ◽  
Electoral System ◽  
Constitutional Democracy ◽  
Electoral Outcomes ◽  
Electoral Laws ◽  
Run Up ◽  
Mixed Electoral System ◽  
2012 Election

While electoral discontent has been the enduring feature of constitutional democracy in Lesotho since independence, disagreement over electoral system is a fairly recent phenomenon. When the country attained independence in 1966 from Britain, electoral system was not necessarily one of the topical issues of pre-independence constitutional negotiations. The major issues were the powers of the monarch, the office of prime minister, the command of the army and many more.  It was taken for granted that the country would use the British-based plurality electoral system.  This is the system which the country used until early 2000s when the electoral laws were reformed to anchor a new mixed electoral system.  When the new electoral laws were ultimately passed in 2001, the country transitioned from a plurality electoral system to a two-ballot mixed member proportional system. By this time, electoral system had acquired prominence in politico-legal discourse in Lesotho.  In the run-up to 2007 elections, bigger political parties orchestrated the manipulation of electoral laws which culminated in clearly distorted electoral outcomes. The manipulations motivated further reforms in the run-up to 2012 election which resulted in the single-ballot mixed member proportional system. The purpose of this paper is to critically evaluate how electoral laws have anchored electoral system reforms throughout the various historical epochs in Lesotho since independence. The paper contends that while the country has been courageous, unlike most of its peers, to introduce far-reaching electoral system changes, the reform of electoral laws has not been so helpful in attaining the higher objectives of political inclusivity, constitutionalism and stability in Lesotho.

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