Computer aided design and analysis of gear tooth geometry

A simulation method for gear hobbing and shaping of straight and spiral bevel gears is presented. The method is based upon an enveloping theory for gear tooth profile generation. The procedure is applicable in the computer aided design of standard and nonstandard tooth forms. An inverse procedure for finding a conjugate gear tooth profile is presented for arbitrary cutter geometry. The kinematic relations for the tooth surfaces of straight and spiral bevel gears are proposed. The tooth surface equations for these gears are formulated in a manner suitable for their automated numerical development and solution

Large-x Parton Distributions

Reliable knowledge of parton distributions at large x is crucial for many searches for new physics signals in the next generation of collider experiments. Although these are generally well determined in the small and medium x range, it has been shown that their uncertainty grows rapidly for x>0.1. We examine the status of the gluon and quark distributions in light of new questions that have been raised in the past two years about "large-x" parton distributions, as well as recent measurements which have improved the parton uncertainties. Finally, we provide a status report of the data used in the global analysis, and note some of the open issues where future experiments, including those planned for Jefferson Labs, might contribute.Comment: LaTeX, 9 pages, 7 figures. Invited talk presented at the ``Workshop on Nucleon Structure in the High x-Bjorken Region (HiX2000),'' Temple University, Philadelphia, Pennsylvania, March 30-April 1, 200

A finite element stress analysis of spur gears including fillet radii and rim thickness effects

Spur gear stress analysis results are presented for a variety of loading conditions, support conditions, fillet radii, and rim thickness. These results are obtained using the SAP IV finite-element code. The maximum stresses, occurring at the root surface, substantially increase with decreasing rim thickness for partially supported rims (that is, with loose-fitting hubs). For fully supported rims (that is, with tight-fitting hubs), the root surface stresses slightly decrease with decreasing rim thickness. The fillet radius is found to have a significant effect upon the maximum stresses at the root surface. These stresses increase with increasing fillet radius. The fillet radius has little effect upon the internal root section stresses

Capitalisation: reflections and practice for project appraisal

Income capitalisation is a widely used in commercial property for valuation, development appraisal or for project feasibility analysis. As a decision-making tool, its technical and philosophical limitations are manifest but often overlooked. If bungled, capitalisation, can lead to ‘white elephant’ projects, investment losses or even corporate collapse. To help avoid such waste, the research reviews some technical issues and philosophical conundrums around capitalisation of property investments. Sound capitalisation practice scopes projects, considers capital market, geographic and institutional context and clarifies valuation base(s). Judicious market comparison, risk diagnostics and analytics filter out noise and render complex data to estimate yields or an appropriate discount rate. For a project feasibility analysis, supplementary salient concerns include wider strategic imperatives, indigenous land rights, stakeholder management, administrative probity and the inclusion of environmental or social spillovers

Land Value Capture and Tax Increment Financing: Overview and Considerations for Sustainable Urban Investment

The paper reviews the notion of Land Value Capture (LVC), its advantages and disadvantages and relevance to for urban growth management. LVC encompasses a wide range of mechanisms, applied in very diverse contexts to monetize ‘windfall’ gains, accruing to landowners because of growth, infrastructure or placemaking projects. Despite widespread conviction that a proportion of these ‘unearned increments’ should somehow be harvested for the wider public good, contention, legal and pragmatic challenges remain. As policy makers confront population pressures, transport needs and inequality, LVC can help bridge infrastructure funding gaps, accelerate housing provision and temper polarisation. Betterment taxes, Tax Increment Finance (TIF) or participatory instruments like land readjustment can target ‘planning gains’ capitalized into land and property values near stations, historic monuments or upgraded precincts. As well as flagging instrument diversity and variable contexts, the literature suggests LVC mechanisms work best in a joined-up policy context. Ironically, spatial LVC schemes like TIF are most likely to fail when the regeneration need is most acute. In America, inadequate governance, scrutiny or auditing undermined schemes to fund transport or improve the public realm. In Europe LVC exists in a variety of modalities but three European examples, suggests it remains underutilized. London megaprojects, UK regional housing schemes and French sprawl, illustrate that policy makers have yet to adequately capture unearned increment

ARIMA modelling of Lithuanian house price index

Purpose – This paper aims to investigate Lithuanian house price changes. Its twin motivations are the importance of information on future house price movements to sector stakeholders and the limited number of related Lithuanian property market studies. Design/methodology/approach – The study employs ARIMA modelling approach. It assesses whether past is a good predictor of the future. It then examines issues relating to an application of this univariate time-series modelling technique in a forecasting context. Findings – As the results of the study suggest, ARIMA is a useful technique to assess broad market price changes. Government and central bank can use ARIMA modelling approach to forecast national house price inflation. Developers can employ this methodology to drive successful house-building programme. Investor can incorporate forecasts from ARIMA models into investment strategy for timing purposes. Research limitations/implications – Certainly, there are number of limitations attached to this particular modelling approach. Firm predictions about house price movements are also a challenge, as well as more research needs to be done in establishing a dynamic interrelationship between macro variables and the Lithuanian housing market. Originality/value – Although the research focused on Lithuania, the findings extend to global housing market. ARIMA house price modelling provides insights for a spectrum of stakeholders. The use of this modelling approach can be employed to improve monetary policy oversight, facilitate planning for infrastructure or social housing as a countercyclical policy and mitigate risk for investors. What is more, a greater appreciation of Lithuania housing market can act as a bellwether for real estate markets in other trade-exposed small country economies

Property market modelling and forecasting: simple vs complex models

Purpose – The commercial property market is complex, but the literature suggests that simple models can forecast it. To confirm the claim, the purpose of this paper is to assess a set of models to forecast UK commercial property market. Design/methodology/approach – The employs five modelling techniques, including Autoregressive Integrated Moving Average (ARIMA), ARIMA with a vector of an explanatory variable(s) (ARIMAX), Simple Regression (SR), Multiple Regression, and Vector Autoregression (VAR) to model IPD UK All Property Rents Index. The Bank Rate, Construction Orders, Employment, Expenditure, FTSE AS Index, Gross Domestic Product (GDP), and Inflation are all explanatory variables selected for the research. Findings – The modelling results confirm that increased model complexity does not necessarily yield greater forecasting accuracy. The analysis shows that although the more complex VAR specification is amongst the best fitting models, its accuracy in producing out-of-sample forecasts is poorer than of some less complex specifications. The average Theil’s U-value for VAR model is around 0.65, which is higher than that of less complex SR with Expenditure (0.176) or ARIMAX (3,0,3) with GDP (0.31) as an explanatory variable models

How long is UK property cycle?

– The purpose of this paper is to assess the duration of the UK commercial property cycles, their volatility and persistence to gauge future market directio

On Compact Routing for the Internet

While there exist compact routing schemes designed for grids, trees, and Internet-like topologies that offer routing tables of sizes that scale logarithmically with the network size, we demonstrate in this paper that in view of recent results in compact routing research, such logarithmic scaling on Internet-like topologies is fundamentally impossible in the presence of topology dynamics or topology-independent (flat) addressing. We use analytic arguments to show that the number of routing control messages per topology change cannot scale better than linearly on Internet-like topologies. We also employ simulations to confirm that logarithmic routing table size scaling gets broken by topology-independent addressing, a cornerstone of popular locator-identifier split proposals aiming at improving routing scaling in the presence of network topology dynamics or host mobility. These pessimistic findings lead us to the conclusion that a fundamental re-examination of assumptions behind routing models and abstractions is needed in order to find a routing architecture that would be able to scale ``indefinitely.''Comment: This is a significantly revised, journal version of cs/050802