Stability evaluation of rotor/bearing system

A stability study of rotor/bearing systems is presented. Even though it was limited to study of a fully lubricated bearing subject to oil whirl, and further limited to low eccentricity region for linearity and with only one type of lubricant, it can be seen that the perturbation methodology, together with the sorting of the impedance terms into direct and quadrature with respect to input force can be very useful to the general study of stability. Further, the concept of active feedback should assist to increase knowledge in rotor system stability. While there remains a large amount of study to be accomplished, perhaps some more tools are available to assist this field of analysis

Steady state and (bi-) stability evaluation of simple protease signalling networks

Signal transduction networks are complex, as are their mathematical models. Gaining a deeper understanding requires a system analysis. Important aspects are the number, location and stability of steady states. In particular, bistability has been recognised as an important feature to achieve molecular switching. This paper compares different model structures and analysis methods particularly useful for bistability analysis. The biological applications include proteolytic cascades as, for example, encountered in the apoptotic signalling pathway or in the blood clotting system. We compare three model structures containing zero-order, inhibitor and cooperative ultrasensitive reactions, all known to achieve bistability. The combination of phase plane and bifurcation analysis provides an illustrative and comprehensive understanding of how bistability can be achieved and indicates how robust this behaviour is. Experimentally, some so-called “inactive” components were shown to have a residual activity. This has been mostly ignored in mathematical models. Our analysis reveals that bistability is only mildly affected in the case of zero-order or inhibitor ultrasensitivity. However, the case where bistability is achieved by cooperative ultrasensitivity is severely affected by this perturbation

Structured Finance Influence on Financial Market Stability – Evaluation of Current Regulatory Developments

In 2007 the world faced one of the biggest financial crises ever. It was the third important financial crisis in the last 12 years. Spillovers to the real economy and moral hazard behaviour of carpetbaggers resulted in enormous pressure on worldwide political institutions to approve a more rigorous regulation on financial institutions and to predict financial crises via early warning systems. We analyzed the performance of structured finance ratings and structured finance issuance/outstanding to detect the main shortcomings of the subprime crisis. Afterwards, we explain the behaviour of market participants with theoretical models and a survey of institutions involved in securitization. With the conclusions of this analysis we evaluate the EU regulation on credit rating agencies and current Basel II enhancements. Finally we can determine that most regulatory enhancements are in accordance with our analyzed shortcomings. Some approaches like the introduction of a leverage ratio are counterproductive and a danger for worldwide economic growth.Structured Finance; Ratings; Regulation; Subprime Crisis; Basel II; Leverage Ratio

New Approach for Temporal Stability Evaluation of Pseudo-Invariant Calibration Sites (PICS)

Pseudo-Invariant Calibration Sites (PICS) are one of the most popular methods for in-flight vicarious radiometric calibration of Earth remote sensing satellites. The fundamental question of PICS temporal stability has not been adequately addressed. However, the main purpose of this work is to evaluate the temporal stability of a few PICS using a new approach. The analysis was performed over six PICS (Libya 1, Libya 4, Niger 1, Niger 2, Egypt 1 and Sudan 1). The concept of a Virtual Constellation was developed to provide greater temporal coverage and also to overcome the dependence limitation of any specific characteristic derived from one particular sensor. TOA reflectance data from four sensors consistently demonstrating stable calibration to within 5%the Landsat 7 ETM+ (Enhanced Thematic Mapper Plus), Landsat 8 OLI (Operational Land Imager), Terra MODIS (Moderate Resolution Imaging Spectroradiometer) and Sentinel-2A MSI (Multispectral Instrument)were merged into a seamless dataset. Instead of using the traditional method of trend analysis (Students T test), a nonparametric Seasonal Mann-Kendall test was used for determining the PICS stability. The analysis results indicate that Libya 4 and Egypt 1 do not exhibit any monotonic trend in six reflective solar bands common to all of the studied sensors, indicating temporal stability. A decreasing monotonic trend was statistically detected in all bands, except SWIR 2, for Sudan 1 and the Green and Red bands for Niger 1. An increasing trend was detected in the Blue band for Niger 2 and the NIR band for Libya 1. These results do not suggest abandoning PICS as a viable calibration source. Rather, they indicate that PICS temporal stability cannot be assumed and should be regularly monitored as part of the sensor calibration process

Stability evaluation of organic Lip Balm

O aumento da demanda global por produtos naturais, cuja produção não envolva nenhum dano ao meio ambiente, tem estimulado o desenvolvimento de cosméticos naturais e, dentro desta categoria, dos produtos orgânicos (que contêm 95% de matérias-primas orgânicas). O protetor labial é um produto cosmético semelhante ao batom que tem a finalidade de prevenir o ressecamento dos lábios, mantendo a hidratação, e protegê-los contra fatores ambientais adversos. Este trabalho envolveu o desenvolvimento de um protetor labial formulado com matérias-primas orgânicas e avaliação dos parâmetros de estabilidade, como ponto de fusão, características organolépticas e funcionalidade (teste de espalhabilidade). A formulação selecionada após o Estudo de Estabilidade Preliminar foi submetida à Avaliação Normal de Estabilidade, nas seguintes condições de armazenamento (temperatura): Ambiente (22,0 ± 3,0 ºC), Estufa (40,0 ± 2,0 ºC) e Geladeira (5,0 ± 1,0 ºC), por 90 dias. Nas condições de armazenamento em geladeira ou ambiente, a espalhabilidade foi adequada, mas a superfície apresentou pontos esbranquiçados, caracterizando o fenômeno chamado fat bloom, que está relacionado à recristalização da manteiga de cacau. O armazenamento à temperatura elevada (40,0 ± 2,0 ºC) provocou perda de funcionalidade, de acordo com o teste de espalhabilidade, e mudança de cor, apesar do aspecto permanecer uniforme, visto que não foi observado o fenômeno fat bloom. O odor manteve-se estável em todas as condições, assim como o ponto de fusão, com valor médio de 72,9 ºC ± 1,7 ºC durante todo o período de avaliação do teste de estabilidade (90 dias).Rising global demand for natural products whose production is harmless to the environment has stimulated the development of natural cosmetics and, within this category, organics (95% organic raw materials). The image of environmentally friendly production is one of the strongest attractions of organic products. Lip balm is a cosmetic product similar to lipstick whose purpose is to prevent lip dryness and protect against adverse environmental factors. The product's characteristics are: resistance to temperature variations, pleasant flavor, innocuousness, smoothness during application, adherence and easy intentional removal. This work involved the development of a lip balm formulated with certified organic raw materials and the execution of stability tests: fusion point determination, evaluation of organoleptic characteristics (color, odor and appearance) and functionality evaluation (spreadability test). The formulation selected after the Preliminary Stability Test was submitted to the Normal Stability Test under the following storage conditions (temperature): Room Temperature (22.0 ± 3.0 ºC), Oven (40.0 ± 2.0 ºC) and Refrigerator (5.0 ± 1.0 ºC), for 90 days. Under the Refrigerator and Room Temperature conditions, spreadability proved adequate, but the surface presented white spots, characterizing the fat bloom, a phenomenon involving the recrystallization of cocoa butter. Storage at 40.0 ± 2.0 ºC (Oven) caused loss of functionality according to the spreadability test, in addition to changes in color, although the aspect was uniform since the fat bloom was not observed (white spots on the surface). The odor remained stable under all conditions as did the melting point, which had a mean of 72.9 ± 1.7 ºC throughout the course of stability testing (90 days)

Transient seepage and slope stability analysis for rainfall induced landslide: a case study

A transient seepage and slope stability analyses were carried out for a case of rainfall-induced landslide in Air Laya Indonesia . The landslide occurred in December 2002 on a dumping area of an open coal mining site. This study examined the mechanism causing the slope failure based on transient analysis between April 21, 2001 and December 1, 2002. The slope profile was simulated using a seepage analyzing tool, VADOSE/W and the soil properties were determined based on field and laboratory data. The saturation profile resulted from seepage analysis was exported to SLOPE/W for the slope stability evaluation. The results show that the main factor contributing to the landslide is the reduction of shear strength due to increase in soil moisture content impelled by the formation of tension cracks on the ground surface of the slope

Traditional Ship Stability Evaluation in Toba Lake

Toba Lake is a major tourist destination in Indonesia, and traditional boats are a popular mode of transportation for residents and tourists alike. However, these traditional ships have been involved in multiple accidents with significant casualties. This study aims to evaluate the stability of the ship according to the conditions of the local water area. The results showed that traditional boats that have been modified to have double decks (to allow for higher customer capacity) have poor stability, especially in bad weather conditions. To maintain sailing safety, it is recommended to recondition the ship into a single deck, avoiding overloads and bad weather. Keywords: Ship Stability, Toba Lake, Evaluatio