bluuebunny/crossref_metadata_2025 huggingface dataset:
Lymphatic pump manipulation mobilizes inflammatory mediators into lymphatic circulation
Authors: Schander Artur , Downey H Fred , Hodge Lisa M
Published: December 2011

Lymph stasis can result in edema and the accumulation of particulate matter, exudates, toxins and bacteria in tissue interstitial fluid, leading to inflammation, impaired immune cell trafficking, tissue hypoxia, tissue fibrosis and a variety of diseases. Previously, we demonstrated that osteopathic lymphatic pump techniques (LPTs) significantly increased thoracic and intestinal duct lymph flow. The purpose of this study was to determine if LPT would mobilize inflammatory mediators into the lymphatic circulation. Under anesthesia, thoracic or intestinal lymph of dogs was collected at resting (pre-LPT), during four minutes of LPT, and for 10 min following LPT (post-LPT), and the lymphatic concentrations of interleukin-2 (IL-2), IL-4, IL-6, IL-10, interferon- γ, tissue necrosis factor α,  monocyte chemotactic protein-1 (MCP-1), keratinocyte chemoattractant, superoxide dismutase (SOD) and nitrotyrosine (NT) were measured. LPT significantly increased MCP-1 concentrations in thoracic duct lymph. Further, LPT increased both thoracic and intestinal duct lymph flux of cytokines and chemokines as compared with their respective pre-LPT flux. In addition, LPT increased lymphatic flux of SOD and NT. Ten minutes following cessation of LPT, thoracic and intestinal lymph flux of cytokines, chemokines, NT and SOD were similar to pre-LPT, demonstrating that their flux was transient and a response to LPT. This re-distribution of inflammatory mediators during LPT may provide scientific rationale for the clinical use of LPT to enhance immunity and treat infection.
Numerical Modeling and Simulation on Seismic Performance of High-Speed Railway Bridge System
Authors: Chen Lingkun , Jiang Lizhong , Zeng Zhiping , Long Weiguo
Published: December 2011

In this paper, the responses of high-speed railway bridge subjected to seismic load were investigated by numerical simulation. Elastic deformation will occur in the bridge system under low-level earthquake; however, the bridge system may enter a nonlinear stage under high-level earthquake. The whole finite element model of the bridge system was set up by means of ANSYS software and self-compiled moment-curvature relationship program, the elastic seismic responses of bridge system and the elastic-plastic deformation of piers considering different vehicle speeds are calculated respectively. The calculation results show that, the earthquake responses of bridge system are increase in general with the increase of vehicle speed and earthquake intensity, and the bottom of piers step into elastic-plasticity stage under high-level earthquake, the plastic hinges occurred at the pier bottom, the pier bottom step into the plastic stage, some measures such as lateral reinforced steel encryption should be taken into account to ensure safety.
Application of a Set of Completed System of Orthogonal Functions in L2[a,b] Space on the Vibration Analysis of Annular Plates
Authors: Wang WeiDong , Cheng Gang , Cheng Quan
Published: December 2011

A type of complete systems of orthogonal functions in L2[a,b] space is introduced into the construction of Green's function of annular plate. A brief and effective method is derived to study the free vibration of annular plates by using the integral equation method. The results obtained not only reveal its briefness and high precision, but also provide a reliable premise for the vibration analysis of more complex annular plates.
Study on Deflection Performance of Radial Tire by Finite Element Method
Authors: Cheng Gang , Zhao Guoqun , Guan Yanjin , Wang Zhonglei
Published: December 2011

In order to improve vehicle safety, the accurate determination of the tire's loading behaviour is necessary in the domain of vehicle dynamics. The interaction between the tire and the surface of the road must be understood thoroughly. A 3D finite element model of the tire-road has been built by using MARC software according to the actual construction of the 195/60R14 radial tire. The rebar model of the radial tire is employed to simulate the complex multilayer cord-rubber composites and directly define the cord directions varying with their positions. The geometric nonlinearity due to large deformation, material nonlinearity and the nonlinear boundary conditions from tire–rim contact and tire–road contact are also considered. The relationships between load and the tire deflection, the tire deformation, the contact stress distribution and the distribution of the contact friction force are discussed.
De-Noising Algorithm for Magnetotelluric Signal Based on Mathematical Morphology Filtering
Authors: Li Jin , Tang Jing-tian , Xiao Xiao
Published: December 2011

In this paper, an effective de-noising algorithm based on mathematical morphology filtering for magnetotelluric sounding data is presented. Magnetotelluric signals are nonlinear, non-stationary, non-minimum phase, they do not meet the basic requirements of the Fourier transform based on the traditional power spectrum estimation. Mathematical morphology filtering is a new signal analysis method developed in recent years for dealing with non-linear, non-stationary signal. This paper briefly introduce the mathematical morphology filtering basic principles and algorithms. According to the properties of structuring elements, the mathematical morphology filtering is designed. Analysis structuring elements type selection program by filtering performance. Based on the measured signal processing, we discussed its application in magnetotelluric sounding data processing and strong interference separation. Experimental results indicate that the proposed method is feasible and can effectively eliminate larger scale disturbance and baseline drift of magnetotelluric sounding data. In addition, the method is efficient to keep the main characteristics of the original signals, and is helpful to improve signal quality and information interpretability for magnetotelluric sounding data.
Achievement of Geothermal Energy Using Ground Heat Exchanger in Ma'En
Authors: Al-Dabbas Mohammed Awwad Ali
Published: December 2011

Geothermal energy in Jordan is a low-emission and renewable source that could provide households and commercial buildings with both heating and cooling. Access to this ‘free’ energy may be available just a few feet underground. Thus, the objectives of this research are:

Designing ground heat exchanger to utilize geothermal energy in heating in which the primary geothermal fluid is exchanged with secondary clean fluid The feasibility of designing ground heat exchanger system to pumping geothermal energy under the climate of Jordan weather in Ma'en area Amount of energy saved

The design procedure involves applying the energy and the momentum equations around the geothermal fluid circuit. The FLUENT software program is used to calculate the ground heat exchanger parameters and the amount of energy saved. Finally, the feasibility study shows that the Geoexchange systems represent a savings to homeowners of around 70% in the heating mode, and up to 50% in the cooling mode compared with conventional fossil fuel systems.
A Pilot Compressed Air Engine
Authors: Ahmed Afzal
Published: December 2011

The air car has a history of development - with proponents and critics - since 1687. As the conventional internal combustion car engine is only 20% efficient, it wastes a considerable amount of energy and will not be feasible, if - for whatever reasons - fossil fuel fall short in supply and therefore, extremely expensive. The drawback of an air engine is that, it is light, requires frequent refilling of the compressed air-tank even for short distances, and the temperature and pressure reduce during expansion in the cylinder. Current research is concerned with alleviating these drawbacks. The good news is that, Motor Development International (MDI) Luxembourg has developed an air engine for a car using a specially designed connecting rod. MDI is now building an air car of 75hp costing US $ 17,800.00 for US roads and can travel up to 1000 miles at 96 mph. In the present study, the concept of double acting steam engine is used by replacing steam with compressed air and the reciprocating motion of piston is governed through flywheel using a solenoid valve. The efficiency of the engine based on input energy of compressed air is about 80%.
A posterior probability based sequential binomial test method for verification of success ratio p
Authors: Liu Q. , An M.
Published: December 2011

Testing the lifetimes of components or products by means of the verification of probability of success ratio p on which to base a statistical probability of the binomial distribution is often a costly and difficult undertaking. Sometimes tests cannot reach at a desirable target, particularly, in the reliability assurance tests. A Bayesian sequential binomial test model (BSBTM) is proposed for obtaining the composite hypothesis of p, which posterior criteria are taken into consideration. In order to get robust decision criteria and closed continuation-sampling regions, a modified Bayesian sequential binomial test model (MBSBTM) is also developed. By using BSBTM and MBSBTM, the upper and lower boundaries of a continuation-sampling region can be determined and the decision criteria can be made. A simulation method of calculating the average sample number (ASN) by using MBSBTM is also presented in this paper. Two case examples are used to demonstrate the proposed BSBTM and MBSBTM methodologies. The results indicate that by using MBSBTM sample numbers can be decided effectively and efficiently in the reliability tests.
Flexural Strength of Sandwich Panel with Lignocellulosic Composites Intermediate Layer – A Statistic Approach
Authors: Fajrin Jauhar , Zhuge Yan , Bullen Frank , Wang Hao
Published: December 2011

In this study, three different types of lignocellulosic composite materials have been incorporated in sandwich panel structure as an intermediate layer. The experiment was statistically designed based on single factor analysis scheme. The results of experiments have been analyzed using analysis of variance (Anova) followed by Tukey's, Fisher's and Dunnet's tests to obtain the information of how significant those materials contribute to the flexural strength of sandwich panel structure. The total number of samples tested was 48 beams. The results show that the introduction of lignocellulosic composites materials, that are hardboard, medium density fibre (MDF) and plywood, has significantly improved the flexural strength of sandwich panel. The range of improvement contributed by the presence of lignocellulosic composites intermediate layer was around 100–150% for samples with balsa core and 130–150% for samples with polystyrene core. The result of this study shows the potential of lignocellulosic composite material to be developed further for producing more sustainable sandwich panel.
Crashworthiness Study on Fuselage Section and Struts under Cabin Floor
Authors: Xue P. , Wang L. , Qiao C.F.
Published: December 2011

Aircraft fuselage and struts under the cabin floor play important impact resisting roles in the crashworthiness of an aircraft. This study first investigates the performance of the struts which support floor beams in a typical fuselage section, and compares the energy absorption characteristics of two typical struts—C shape and Wide-flange shape. Then, the vertical drop numerical test of a fuselage section at a velocity of 9 m/s is conducted. The performances of the aircraft fuselage with different struts in cross section and orientation angle are compared. The results show that the specific energy of Wide-flange is higher than that of C shape when subjected to axial impact load. However, in a fuselage section, the struts are subjected to a complex loading condition, resulting in complex impact energy dissipation process in the vertical crash process. The bending rigidity of Wide-flange is greater than that of C shape, as a result that the initial acceleration peak transferred by the strut with Wide-flange shape to the seat is greater than that transferred by C shape strut. The orientation angle of the struts also affects the crashworthiness of the fuselage section.
Middle Furongian (late Cambrian) shumardiids from the Sesong Formation, Taebaek Group, Korea
Authors: Park Tae-Yoon , Choi Duck K.
Published: December 2011

The trilobite family Shumardiidae is characterized by small size, lack of eyes, yoked librigenae, and a small number of thoracic segments. Here we report the successive occurrence of three middle Furongian shumardiid species from the Sesong Formation of Korea: Elaphraella? taebaeksanensis n. sp., Elaphraella microforma, and Elaphraella nodus. They appear to represent the oldest shumardiid morphology known so far. This genus lacks the anterolateral swellings on the glabella and has a conical glabella. Its yoked librigenae also encompass a comparatively wide genal field. Elaphraella? taebaeksanensis has a highly inflexed facial suture which may reflect the presence of small palpebral lobes. Taken together, the plesiomorphic morphology of the Shumardiidae can be summarized as having a conical glabella, small palpebral lobes, highly arched anterior cephalic margin, a wide librigenal field, and no anterolateral swellings on the glabella.
Psychosocial Factors Associated With Mouth and Throat Cancer Examinations in Rural Florida
Authors: Riley Joseph L. , Dodd Virginia J. , Muller Keith E. , Guo Yi , Logan Henrietta L.
Published: December 2011

Objectives. We examined the knowledge and prevalence of mouth and throat cancer examinations in a sample drawn from rural populations in north Florida.

Methods. Telephone interviews were conducted across rural census tracts throughout north Florida in 2009 and 2010, in a survey that had been adapted for cultural appropriateness using cognitive interviews. The sample consisted of 2526 respondents (1132 men and 1394 women; 1797 Whites and 729 African Americans).

Results. Awareness of mouth and throat cancer examination (46%) and lifetime receipt (46%) were higher than reported in statewide studies performed over the past 15 years. Only 19% of the respondents were aware of their examination, whereas an additional 27% reported having the examination when a description was provided, suggesting a lack of communication between many caregivers and rural patients. Surprisingly, anticipated racial/ethnic differences were diminished when adjustments were made for health literacy and several measures of socioeconomic status.

Conclusions. These findings support the notion that health disparities are multifactorial and include characteristics such as low health literacy, lack of access to care, and poor communication between patient and provider.
Economic Foundations of Valuation Discounts
Authors: Sansing Richard C.
Published: December 2011

This paper develops and analyzes two models of asset valuation from which the appropriate discounts for lack of marketability, blockage, and minority ownership are derived. The analysis of the first model shows that a lack of prospective buyers is a necessary but not sufficient condition for a discount for lack of marketability. Heterogeneous beliefs among prospective buyers regarding the value of the asset are also required. A consequence of this result is that the proper marketability discount for an interest in a partnership that holds easily valued investment assets is zero. Analysis of the second model shows that a discount for owning a minority interest reflects the ability of a majority owner to indirectly transfer wealth to himself at the expense of the minority owner. If a discount exists, it is decreasing in the cost of the transfer to the corporation and decreasing in the ownership interest of the majority shareholder.
The Effect of Taxes on Acquisition Price and Transaction Structure
Authors: Henning Steven L. , Shaw Wayne H. , Stock Toby
Published: December 2011

The purpose of this paper is to investigate the effect of the target's tax status on the structure of taxable corporate acquisitions. Specifically, we examine how the taxes imposed on the parties to the transaction are shared. Our results suggest the acquirer bears target tax costs through higher acquisition prices. In addition, our results also suggest that the acquirer pays little, if anything, to the target for the use of target net operating losses. Finally, we find that the target's tax status affects the transaction structure since targets with higher marginal tax rates are more likely to desire contingent payments in the contract.
The Effects of Goodwill Tax Deductions on the Market for Corporate Acquisitions
Authors: Ayers Benjamin C. , Lefanowicz Craig E. , Robinson John R.
Published: December 2011

We analyze the effect of the tax deduction for goodwill amortization provided by the Omnibus Budget Reconciliation Act of 1993 (OBRA) on the market for corporate acquisitions. We analyze a sample of taxable corporate acquisitions, including acquisitions of subsidiaries, private firms, and public firms, occurring over the period 1990 through 1996. We assess the impact of the goodwill legislation by (1) quantifying the frequency and size of qualifying acquisitions and comparing these acquisitions to nonqualifying acquisitions pre- and post-OBRA and (2) investigating if and how the goodwill amortization deduction influenced the premium paid for qualifying corporate acquisitions. We estimate a regression of acquisition premiums on target-firm characteristics including a proxy for purchased goodwill. We find that acquisitions qualifying for goodwill amortization comprise less than 17 percent of sample taxable corporate acquisitions before OBRA, and this percentage does not increase after the enactment of OBRA. Nonetheless, our regression results indicate that the OBRA goodwill provisions did contribute to a significant increase in acquisition premiums associated with purchased goodwill for qualifying transactions. Thus, rather than operate as a subsidy to acquiring firms, we find that a majority of the tax benefits associated with the goodwill amortization deduction accrues to target-firm shareholders.
The Impact of Explicit and Implicit State Taxation of U.S. Government Obligations on the Structure of Banks' Investment and Financing Portfolios
Authors: Beatty Anne , Harris David G.
Published: December 2011

In this paper we examine the effects of differential state taxation of U.S. Government obligations (USOs) on how banks structure their investment and financing portfolios, the riskiness of banks' assets, and how implicit tax effects are impounded in investments' returns. Twenty-seven states tax USOs (taxing states) and 23 states and the District of Columbia do not (nontaxing states). We find that banks in taxing states hold significantly greater amounts of USOs, which are among the least risky assets banks can hold, and we find that these banks hold a less risky mix of assets. Consistent with compensating for the lower risk of their asset mix, we also find that these banks hold less capital. Taken together, these results are consistent with effective bank regulation enforcement, since banks have similar capital to risk-weighted asset ratios in spite of differing tax-based incentives to hold riskless assets. We also examine the impact of implicit taxes on banks' USO holdings and related accounts and find that in taxing states banks' USO investments are decreasing in their state tax rate. We also find corresponding increases in asset riskiness for which banks do not appear to fully compensate in the highest state-tax-rate states. Finally, the effects shown in this paper are economically significant. For example, we find that banks operating in taxing states hold, on average, 40 percent less USOs than do banks in nontaxing states.
Public Utility Old Money Preferred Stocks
Authors: Atwood T. J.
Published: December 2011

Public utilities can claim a partial dividends-paid deduction on “old money” preferred stock (OMPS) but the 42 percent dividends-received deduction (DRD) allowed to corporate investors is lower than the 70 percent DRD allowed on other types of preferred stock. This study provides evidence that the implicit tax borne by OMPS is lower than that of other preferred stock and that the estimated implicit tax associated with the 70 percent DRD is much higher than prior research suggests. Evidence is also presented indicating that marginal investors in OMPS are corporations with marginal tax rates between 26.3 percent and 27.2 percent. Finally, this study provides evidence that public utilities use OMPS financing in addition to, rather than as a substitute for, other types of preferred stock. This result suggests that tax considerations influence public utility managers' capital structure decisions even though tax savings flow through to ratepayers in the rate-making process.
CEO Bonus Pay, Tax Policy, and Earnings Management
Authors: Reitenga Austin , Buchheit Steve , Yin Qin Jennifer , Baker Terry
Published: December 2011

In 1993, Congress passed Internal Revenue Code Section 162(m), which eliminated the tax deductibility of nonperformance-based executive compensation over $1 million. Recent research indicates that, as intended, Code Section 162(m) has strengthened the link between executive pay and firm performance.

Although 162(m) apparently has changed executive compensation in a way desired by Congress, we hypothesize that 162(m) has indirectly influenced the financial-reporting process. Specifically, we hypothesize and find evidence to support the following: for numerous reasons associated with “qualifying” a compensation plan per Code Section 162(m), executives in firms that qualify their compensation plans receive relatively low pay when their firm's financial performance is extreme. Because these executives receive relatively low pay for extreme financial performance, an incentive exists to smooth reported earnings over time in order to maximize long-term compensation. The relatively smooth earnings patterns that we observe in qualified firms are related to the use of discretionary accruals.

Our results appear robust to alternative sampling and modeling techniques. As such, our evidence suggests that a tax policy designed to curb allegedly excessive executive compensation has indirectly affected the quality of reported earnings.
The Journal of the American Taxation Association 1979–2000: Content, Participation, and Citation Analyses
Authors: Hutchison Paul D. , White Craig G.
Published: December 2011

This study uses three databases to identify and discuss trends within The Journal of the American Taxation Association (JATA) for the 1979 through 2000 time period. This research reports on institutional involvement of the authors publishing in JATA and examines the extent of citations of JATA articles within the journal itself and in other academic, accounting journals. Methodologies utilized are content, participation, and citation analyses.

A review of the data suggests that JATA went through a major shift in emphasis during the late 1980s and early 1990s. This shift brought a narrowing of focus on tax topics and research methodologies consistent with the Scholes and Wolfson paradigm of tax research. In addition, participation in JATA shifted more toward Assistant Professors, although this gap has begun to close in recent years.
Using Declarative Knowledge to Improve Information Search Performance
Authors: Roberts Michael L. , Ashton Robert H.
Published: December 2011

Knowledge acquisition theory holds that superior judgment/decision-making performance depends on procedural knowledge, which, in turn, results from experience (practice and feedback). This research demonstrates that, under certain conditions, performance can be improved by exposure to declarative knowledge alone, without costly practice and feedback. Practicing tax accountants and graduate tax students participated in a computer-interactive study to improve tax research performance. Using a pretest-posttest design, knowledge and performance were measured prior to, and after, a treatment group (but not a control group) was exposed to a declarative knowledge intervention intended to enhance their knowledge of the content and structure of the Internal Revenue Code. Comparison of the treatment and control groups on posttest knowledge and posttest performance using commercial electronic tax research systems confirmed that the intervention was effective in improving both efficiency and effectiveness in research tasks. Implications for theory and future research are explored.
The Impact of Floors and Phase-Outs on Taxpayers' Decisions and Understanding of Marginal Tax Rates
Authors: Rupert Timothy J. , Single Louise E. , Wright Arnold M.
Published: December 2011

Tax provisions that reduce deductions and credits by imposing floors and phase-outs have become an increasingly popular tool used by Congress. However, these provisions also obscure the marginal tax rate, thereby potentially impairing the ability of taxpayers to make optimal decisions.

We investigate the effects of floors and phase-outs on taxpayers' ability to determine their correct marginal tax rates and how this may affect tax-rate-dependent investment decisions. To investigate these potential effects we created an experimental setting in which taxpayers (89 M.B.A. students) were asked to maximize their after-tax income by choosing between a taxable and nontaxable bond. Each participant was assigned to one of three experimental tax systems: low complexity with no floors or phase-outs, medium complexity with one floor, and high complexity with both a floor and phase-out. The effective marginal tax rate was the same in each condition. The results indicate that decision performance was significantly better for participants facing the low complexity system than those in the medium or high complexity systems.
Competitive, Political, and Economic Factors Influencing State Tax Policy Changes
Authors: Omer Thomas C. , Shelley Marjorie K.
Published: December 2011

We investigate state tax competition for capital and jobs, focusing on the business income apportionment formula. We look for associations between states' apportionment formula changes and competing states' changes using event history analysis. We test for a positive association between our tax competition proxies and apportionment formula change while controlling for economic, political, and regional diffusion influences on tax policy. Our results support the hypothesized positive association. We conclude that state governments compete for capital and jobs and respond to their competitors' tax policy decisions with conforming policy changes. Our study contributes to the empirical tax literature on state and local tax policy.
Disclosure of Managers' Forecasts in Interim Financial Statements: A Study of Effective Tax Rate Changes
Authors: Bauman Mark P. , Shaw Kenneth W.
Published: December 2011

This study examines whether managerial forecasts of annual effective tax rates, disclosed in interim financial statements, are useful in predicting future quarterly earnings, are incorporated in financial analysts' forecasts of quarterly earnings, or are impounded in stock prices. The integral view of interim financial reporting requires managers to make their best estimate of the effective income tax rate (ETR) to be in effect for the full fiscal year. Thus, the ETR reflected in interim financial statements represents the disclosure of certain private information regarding management's expectations for forthcoming earnings. Auditors review the income tax provision in conjunction with the release of interim financial statements, arguably lending credibility to management's ETR forecast. Our empirical analyses show that interim effective tax rate disclosures are useful in predicting next-quarter earnings. However, financial analysts generally under-utilize this information when firms report large decreases in ETR. Surprisingly, small ETR increases are related to higher future earnings, and a zeroinvestment strategy based on small ETR increases yields significant abnormal returns. In sum, although interim ETRs are useful in predicting future earnings, both financial analysts and stock market investors fail to fully impound the earnings implications of interim effective tax rate changes in their decisions.
Noncash Charitable Giving: Evidence of Aggressive Taxpayer Reporting Following a Compliance Change
Authors: Buchheit Steve , Lightner Teresa , Masselli John J. , Ricketts Robert C.
Published: December 2011

Treasury Decision (TD) 8002 significantly relaxed the substantiation requirements for deducting noncash charitable contributions under $501 for tax years 1985 and after. We present evidence that TD 8002 caused a significant change in taxpayer behavior. Specifically, the relatively stable percentage of taxpayers who claimed zero noncash charitable deductions in years prior to TD 8002 decreased consistently and significantly after TD 8002's implementation. The decrease in zero noncash deduction taxpayers was largely replaced by taxpayers who reported noncash charitable deductions for amounts just under TD 8002's relaxed substantiation requirement (i.e., amounts just under $501). We present a series of tests supporting the contention that the increase in reported noncash charitable deductions is largely attributable to more aggressive reporting behavior rather than increased charitable giving.
Effects of Mutual Coupling of Radiating Antennas on an Adaptive Radar Detector
Authors: De Nicola Silvio , De Maio Antonio , Farina Alfonso , Fiorini Michele , Infante Leopoldo , Piezzo Marco
Published: December 2011

Effects of Mutual Coupling of Radiating Antennas on an Adaptive Radar Detector

In this paper, we address the adaptive detection/classification of signals in a homogenous interference environment. We refer to a radar system equipped with a phased array antenna and account for both the presence of mutual coupling between radiating antennas and a possible coherent interferer impinging on the array mainbeam. To deal with this scenario, we adopt a two-stage detection/classification scheme, enjoying the Costant False Alarm Rate (CFAR) property, to discriminate between target detection and coherent interferer rejection. Finally, we evaluate the system performance via Monte Carlo simulations. The results show that our system has interesting rejection capabilities and satisfactory detection levels. As a consequence, it could be successfully applied in real scenarios where mutual coupling is present.
Modulation-Mode Assignment in SVD-Aided Downlink Multiuser MIMO-OFDM Systems
Authors: Aust Sebastian , Ahrens Andreas , Benavente-Peces César
Published: December 2011

Modulation-Mode Assignment in SVD-Aided Downlink Multiuser MIMO-OFDM Systems

Multicarrier transmission such as OFDM (orthogonal frequency division multiplexing) is an established technique for radio transmission systems and it can be considered as a promising approach for next generation wireless systems. However, in order to comply with the demand on increasing available data rates in particular in wireless technologies, systems with multiple transmit and receive antennas, also called MIMO (multiple-input multiple-output) systems, have become indispensable for future generations of wireless systems. Due to the strongly increasing demand in high-data rate transmission systems, frequency non-selective MIMO links have reached a state of maturity and frequency selective MIMO links are in the focus of interest. In this field, the combination of MIMO transmission and OFDM can be considered as an essential part of fulfilling the requirements of future generations of wireless systems. However, single-user scenarios have reached a state of maturity. By contrast multiple users' scenarios require substantial further research, where in comparison to ZF (zero-forcing) multiuser transmission techniques, the individual user's channel characteristics are taken into consideration in this contribution. The performed joint optimization of the number of activated MIMO layers and the number of transmitted bits per subcarrier shows that not necessarily all user-specific MIMO layers per subcarrier have to be activated in order to minimize the overall BER under the constraint of a given fixed data throughput.
Use of Analytic Hierarchy Process to Prioritize Network-Level Maintenance of Pavement Segments with Multiple Distresses
Authors: Farhan J. , Fwa T. F.
Published: December 2011

In network-level pavement management, maintenance prioritization of pavement segments usually involves determining the relative priorities of pavement segments with several distresses of various types and severity levels. A widely adopted practice is to assign maintenance priority to each pavement segment with a priority index computed with an empirical mathematical equation. Though convenient to use, the computed numerical index does not have a clear physical meaning, and it may not accurately and effectively convey the priority assessment or intention of highway agencies and engineers. The analytic hierarchy process (AHP) has been adopted to overcome this limitation. The AHP was previously applied to establish the relative pavement maintenance priorities of single pavement distress types with different severity levels. The problem of establishing maintenance priorities of pavement segments with multiple distresses is much more complex. Many more decision levels and pairwise comparisons must be made because of many possible combinations of distress types and severities. The AHP formulation of the problem is presented, along with a demonstration of an example problem consisting of 30 multidistress pavement segments. The solution of priority ratings by the AHP is compared with the corresponding solution by the widely adopted PAVER pavement maintenance procedure. The reasonableness of the two solutions is compared with the priority ratings obtained from a direct assessment method that provides the baseline reference for comparison.
Axle Load Power for Pavement Fatigue Cracking
Authors: Guler S. Ilgin , Madanat Samer
Published: December 2011

Deterioration equivalence factors are an essential part of deterioration models used in pavement management systems. For accurate cost estimation, it is important to determine the correct axle load power. The data set from the AASHO Road Test was used to estimate a hazard rate function. The results showed that the axle load power for initiation of fatigue cracking was significantly higher than the power typically assumed. This result has implications for pavement deterioration charging schemes that are based on marginal cost pricing.
Linear Mixed-Effects Models for Preliminary Analysis of Flexible Pavement Serviceability Index Data
Authors: Ker Hsiang-Wei
Published: December 2011

Multilevel data are common in many fields. Because of the hierarchical data structure, multilevel data are often analyzed with linear mixed-effects (LME) models. Exploratory analysis, statistical modeling, and examination of the model fit of LME models are more complex than those of standard multiple regressions. A systematic modeling approach that uses visual-graphical techniques and LME models is proposed and demonstrated with the original AASHO Road Test flexible pavement serviceability index data. The proposed approach includes exploring the growth patterns at both group and individual levels, identifying the important predictors and unusual subjects, choosing suitable statistical models, selecting a preliminary mean structure, selecting a random structure, selecting a residual covariance structure, model reduction, and examination of the model fit.
Integrated Maintenance and Expansion Planning for Transportation Network Infrastructure
Authors: Gao Lu , Xie Chi , Zhang Zhanmin , Waller S. Travis
Published: December 2011

Maintenance of existing road network infrastructure and expansion of networks with new facilities are two major investment categories in the transportation system. Road maintenance projects optimize the scheduling of maintenance activities so that pavement is in good condition and so that road expansion projects add extra capacity to a road network to improve mobility. The two problems are usually considered separately in practice; however, an integrated approach to these two problems was proposed. The road maintenance problem and the road expansion problem were formulated together as a mixed-integer, nonlinear, bilevel optimization problem with the objective of optimizing overall system performance. A solution algorithm that was based on the generalized Benders decomposition theory, significantly relaxing computational complexity, was proposed. Finally, a numerical case study demonstrated the proposed problem and the algorithm used to solve it. The benefit of the integrated model over models that consider only maintenance or expansion projects was discussed.
Data Collection to Support Implementation of the Mechanistic–Empirical Pavement Design Guide for County Roads
Authors: Souliman Mena I. , Mamlouk Michael , Zapata Claudia E. , Cary Carlos E.
Published: December 2011

Evaluation and calibration of the Mechanistic–Empirical Pavement Design Guide (MEPDG) has been attempted by various agencies throughout the United States. Agencies interested in adopting the MEPDG procedure must prepare a practical implementation plan that fits local conditions. The first step in the implementation plan is collection of design input data and establishment of a database for inputs. A 3-year study was conducted at Arizona State University to establish a database to support MEPDG implementation for the Maricopa County, Arizona, Department of Transportation. The implementation program included testing of asphalt binders, hot-mix asphalt dynamic modulus, and unbound-materials resilient modulus; development of climatic weather stations and training material; and collection of traffic data. The collected information can be used to calibrate the MEPDG distress models to county conditions and verify such models. The input parameters can serve as a framework for similar highway agencies and help ensure the successful implementation of the MEPDG.
Relation of Flow, Speed, and Density of Urban Freeways to Functional Form of a Safety Performance Function
Authors: Kononov Jake , Lyon Craig , Allery Bryan K.
Published: December 2011

Constructive discussion of the appropriate choice for the functional form of safety performance functions (SPFs) is generally absent from research literature on road safety. Among researchers who develop SPFs, there appears to be a consensus that the underlying randomness in accident counts is well described by the negative binomial (NB) distribution. The underlying phenomenon itself, however, is not well understood and is rarely discussed. The choice of the regression equation is usually not explained or documented. Researchers most commonly use the power function, possibly because most generalized linear modeling (GLM) statistical packages can accommodate the power function with little effort. The modeling process, however statistically rigorous, at times seems disconnected from the physical phenomenon that it is trying to describe. The disconnect, however, has attracted only limited interest from researchers to date. Accidents on an urban freeway are a by-product of traffic flow; therefore, changes in the flow parameters may give clues about the probability of accident occurrence and changes in accident frequency. This study related traffic flow parameters, such as speed and density, to the choice of the functional form of the SPF. It compared SPF models for urban freeways developed with sigmoid and exponential functional forms with the use of data from Colorado and California and contrasted the cumulative residual (CURE) plots of the models. SPFs developed around a sigmoid functional form through the use of neural network (NN) methodology suggested underlying relationships between safety and traffic flow characteristics. CURE plots for NN-generated SPFs generally showed a better-quality model fit when compared with power-function SPFs, which were developed in the GLM framework with an NB error structure.
Disaggregate Exposure Measures and Injury Frequency Models of Cyclist Safety at Signalized Intersections
Authors: Miranda-Moreno Luis F. , Strauss Jillian , Morency Patrick
Published: December 2011

This paper proposes a new approach to represent cyclist risk exposure. This approach considers disaggregate motor vehicle and cyclist flows and develops cyclist injury frequency models. Three definitions of risk exposure were used in this research, including aggregated flows, motor vehicle flows aggregated by movement type, and potential conflicts between motor vehicles and cyclists. As an application environment, a large sample of signalized intersections on the island of Montreal, Quebec, Canada, was used, along with data that comprised disaggregate motor vehicle and cyclist flows. Several negative binomial models were fitted to the data. This study showed that cyclist collisions were sensitive to changes in both cyclist and motor vehicle flows. A 10% increase in bicycle flow was associated with a 4.4% increase in the frequency of cyclist injuries. A 10% increase in the total number of motor vehicles that passed through the intersection would result in a 3.4% increase in cyclist injury occurrence. When motor vehicle flows were considered on the basis of movement type, right-turn movements had a great effect on injury occurrence. Similar results, which identified right turns as having the greatest effect on cyclist injuries, were produced when the impact of potential conflicts was determined. The number of bus stops in the proximity of the intersection increased cyclist injury occurrence. Some geometric design factors, such as the presence of a median, parking entrance, and the number of intersection legs, were tested. The effect, however, was found to be statistically nonsignificant.
Conflict Models for Single-Lane Roundabout Slip Lanes from Microsimulation
Authors: Al-Ghandour Majed N. , Schroeder Bastian J. , Williams Billy M. , Rasdorf William J.
Published: December 2011

Conflict patterns at single-lane roundabouts with and without slip lanes were evaluated and compared through VISSIM, the microscopic simulation program for multimodal traffic flow modeling, and surrogate safety assessment model (SSAM) analysis. From a sensitivity analysis of several volume distribution scenarios of the percentage of turning traffic, five zone-based conflict prediction models were developed through the use of Poisson regression. The models captured simulated conflict differences that resulted from the addition of a right-turn slip lane. The models were evaluated under three exit control scenarios (yield, stop, and free-flow merge). With SSAM analysis, the models predicted the occurrence of conflicts for roundabout zones with different R-squared values, which ranged from .69 to .97. The models were compared with national and inter-national crash prediction models for single-lane roundabouts and were further validated by actual crash data from 10 single-lane roundabouts in the city of Carmel, Indiana. The number of conflicts for a single-lane roundabout was predicted as a function of approach entry, circulation, and slip lane traffic flows and was determined to be sensitive to the slip lane exit type. Results confirmed that conflicts in the merge area were more frequent than in the roundabout approach area and that the installation of a free-flow slip lane exit type reduced overall conflict occurrence. The results demonstrated the usefulness of SSAM analysis for evaluating roundabout safety and developing an empirical relationship between simulated conflicts and field-observed crashes.
Understanding Causality of Intersection Crashes
Authors: Miller John S. , Garber Nicholas J. , Korukonda Santhosh K.
Published: December 2011

Intersection crashes in the United States account for more than one-fifth of all highway fatalities. Crash, geometric, and roadway information can help identify crash causes. How such elements can serve this function, however, may not be clear to database users because of the random variation inherent in crashes. For this reason, classification trees and crash estimation models (CEMs) were developed from a 6-year data set, which contained more than 70,000 crashes that occurred at more than 6,000 intersections in Northern Virginia. The trees showed that specific causal factors, such as surface condition, indicated whether a given crash was rear-end or angle. Because such trees suggested that intersection crashes were not purely random, CEMs for 17 intersection classes were developed on the basis of traffic control, number of approaches and lanes, and rural versus urban area to predict four crash frequencies: rear-end, angle, injury, and total. The 68 CEMs showed deviance-based, pseudo–R-squared values between .07 and .74 and varied by intersection class. Of the nine angle crash models in which risk increased by making the approaches undivided, the increase varied between 43% and 154%. Two lessons emerged. First, the small proportion of variables that successfully classified most rear-end and angle crashes should be given increased attention to ensure that these data elements are recorded accurately at the crash scene. The methodology used in this study showed that much of the tree factor space (81%) was composed of only 10 variables. Second, facility-specific intersection CEMs should be developed because a geometric variable may be a surrogate for other phenomena.
Heat of Hydration for Cement
Authors: Stutzman Paul , Leigh Stefan , Dolly Kendall
Published: December 2011

The heat of hydration of hydraulic cements depends on a complex set of phase dissolution and precipitation reactions following the addition of water. Heat of hydration is currently measured in one of two ways: acid dissolution of the raw cement and a hydrated cement after 7 days or isothermal calorimetry. In principle, the heat of hydration should be predictable from knowledge of the cement composition and perhaps some measure of the cement fineness or total surface area. The improved mineralogical estimates provided by quantitative X-ray powder diffraction, together with improved statistical data exploration techniques that examine nonlinear combinations of candidate model constituents, were used to explore alternative predictive models for the 7-day heat of hydration. An exploratory tool, called “all possible alternating conditional expectations,” was created by combining all possible subsets regression with alternating conditional expectation to judiciously select variables within an explanatory variable class and subsets of variables across explanatory variable classes exhibiting the highest potential predictive power for additive nonlinear models for 7-day heat of hydration. Although a single, strong model for 7-day heat of hydration did not emerge from analyses, general conclusions were drawn. Good-fitting models included a key structural mineralogical phase (belite preferred); calcium sulfate phase (bassanite preferred); total fineness or surface area component (Blaine fineness preferred); and ferrite in conjunction with iron oxide, or aluminate, or cubic aluminate.
New Approach to Calibrate the Mortar Flow Table
Authors: Ferraris Chiara , Azari Haleh
Published: December 2011

The flow table is a standardized test that is widely used to qualify a mortar for compressive strength and air content. The flow table is also the only standard test to quantify the workability of a mortar. Therefore, the calibration of this device is paramount, and it is done today by preparing a reference material consisting of a mixture of silica powder and oil. The two materials are mixed; tests are performed with the use of the reference flow table located in the Cement and Concrete Reference Laboratory. This flow table is identical to commercial versions currently used, and the values obtained with this flow table are considered the reference values for calibrating flow tables in the United States. This is an empirical procedure and relies heavily on one device that could break or generate results that can drift over time. This study reviewed the manufacturing process of the reference material, provided historical data, and proposed a more scientifically based approach to develop an improved reference material.