bluuebunny/crossref_metadata_2025 huggingface dataset:
Microshear Bond Strength of Resin Cements to Lithium Disilicate Substrates as a Function of Surface Preparation
Authors: Lise DP , Perdigão J , Van Ende A , Zidan O , Lopes GC
Published: March 2015

Objectives

To investigate the effect of hydrofluoric acid (HF) etching, silane solution, and adhesive system application on the microshear bond strength (μSBS) of lithium disilicate glass-ceramic (LD) to three resin cements.

Materials and Methods

Circular bonding areas were delimited on the lithium disilicate surfaces using a perforated adhesive tape. Specimens were assigned to 18 subgroups (n=12) according to surface treatment: NT = no treatment; HF = 4.8% HF for 20 seconds; silane solution: (1) no silane; (2) Monobond Plus, a silane/10-methacryloyloxydecyl dihydrogen phosphate solution for 60 seconds; (3) Monobond Plus+ExciTE F DSC, a dual-cure adhesive; and resin cement: (1) Variolink II, a bisphenol A diglycidyl ether dimethacrylate (bis-GMA)–based, hand-mixed, dual-cure resin cement; (2) Multilink Automix, a bis-GMA–based, auto-mixed, dual-cure resin cement; (3) RelyX Unicem 2, a self-adhesive, auto-mixed, dual-cure resin cement. Tygon tubes (Ø=0.8 mm) were used as cylinder matrices for resin cement application. After 24 hours of water storage, the specimens were submitted to the μSBS test. Mode of failure was evaluated under an optical microscope and classified as adhesive, mixed, cohesive in resin cement, or cohesive in ceramic. Data were statistically analyzed with three-way analysis of variance and Dunnett test (p<0.05).

Results

When means were pooled for the factor surface treatment, HF resulted in a significantly higher μSBS than did NT (p<0.0001). Regarding the use of a silane solution, the mean μSBS values obtained with Monobond Plus and Monobond Plus+ExciTE F DSC were not significantly different but were higher than those obtained with no silane (p<0.001). Considering the factor resin cement, Variolink II resulted in a significantly higher mean μSBS than did RelyX Unicem 2 (p<0.03). The mean μSBS for Multilink Automix was not significantly different from those of Variolink II and RelyX Unicem 2. According to Dunnett post hoc test (p<0.05), there was no significant difference in μSBS between the different resin cements for HF-etched and silanized (with or without adhesive application) LD surfaces.

Conclusion

LD may benefit from pretreatment of the inner surface with HF and silanization, regardless of the resin cement used.
Examination of Stigmatizing Beliefs about Depression and Stigma-Reduction Effects of Education by Using Implicit Measures
Authors: Kashihara Jun
Published: March 2015

Stigmatizing beliefs about depression have been viewed as a barrier to seeking professional treatments. To reconsider frameworks used in previous research, the present study utilized Brief Implicit Association Tests (BIATs) and examined the following two topics: (i) whether participants tend to hold dangerous beliefs about depression, and (ii) whether stigmatizing beliefs can be reduced through education. Japanese university students (48 women, 82 men; M age = 20.2yr.) voluntarily participated in the study and were randomly assigned to three conditions in which they received different educational texts (biomedical, psychosocial, and bio-psychosocial). Participants completed repeated assessments (baseline, post-education, and 4-wk. follow-up), in which they were administered BIATs measuring beliefs about being weak-willed and dangerousness of people with depression, along with explicit measures of blameworthiness, dangerous beliefs, and of other related variables. BIATs at baseline indicated that the participants did not tend to hold the belief about dangerousness. There was no significant reduction of beliefs about being weak-willed and dangerousness of people with depression, which were measured by BIATs, after reading the educational texts.
Dissimilation of soil humus in forest with pure stands and its relationship with other bio-chemical properties in the semi-arid windy region of the Loess Plateau, China
Authors: Zhang Xiaoxi , Liu Zengwen , Bing Yuanhao , Zhu Bochao , Trung Luc Nhu , Chen Kehao
Published: March 2015

Dissimilation of soil humus in 7 typical forests with pure stands in the semiarid windy region of the Loess Plateau in China was investigated. In addition, its relationships with other bio-chemical characteristics were assessed by canonical correlation analysis. The results was as follows: (1) Pinus tabuliformis Carrière forest had the lowest humus content and the worst stability among 7 forests with pure stands; Populus simonii Carrière forest had low humus content and worse stability; Robinia pseudoacacia L. forest had moderate humus content but the best stability; Salix matsudana Koidz. forest had moderate humus content and bad stability; Hippophae rhamnoides L. forest had high humus content and the best stability; Caragana microphylla Lam. forest had high humus content and moderate stability; Amorpha fruticosa L. forest had the highest humus content and benign stability; (2) Large microbial biomass and sufficient available P would accelerate the formation of humic acid and fulvic acid, respectively. High available N, P and Fe contents and high urease and protease activity were conducive to increase the humus stability. The particularity of community environment and litter properties of pure stands were identified as the key reasons for the humus dissimilation, thus mixed-reformation or establishing ground vegetation would be feasible ways to improve humus properties in forest with pure stands.
Assessing the pre-REDD policies of countries with substantial forest area growth
Authors: Hu Xin , Hodges Donald G. , Shi Guoqing
Published: March 2015

Based on the method of Compensated Successful Efforts, this paper proposes a structural variables model to assess pre-REDD+ (Reducing Emission from Deforestation and Degradation plus) policies; selecting economic development, population growth, initial forest area, agricultural commodity export prices, and timber prices as structural variables, and empirically analyzes 11 high-forest-growth countries’ policies from 1992 to 2011. Results show that the forest area growth rate was negatively correlated with the initial forest area and agricultural commodities export prices, and positively correlated with population density, GDP per capita, and timber export prices. China and India’s entity fixed effects are more significant; in different periods the rate of actual forest area growth exceeded that of structural forest area growth in 11 countries. Overall, Compensated Successful Efforts proved to be useful for evaluating the effects of the high forest area growth country policies. Regardless, these countries should join REDD+ organizations and continue enhancing their forest management and increasing forest area. As part of this effort, REDD+ negotiations should consider fully compensation mechanisms for these countries to attract more countries and promote the progress of international climate negotiations.
Diquat-induced cytotoxicity on Vero and HeLa cell lines: effect of melatonin and dihydromelatonin
Authors: Moravčík Roman , Okuliarová Monika , Kováčová Elena , Zeman Michal
Published: March 2015

Diquat dibromide is a moderately toxic contact herbicide belonging to the bipyridyl group of redox-active compounds that induce a strong oxidative damage. Melatonin (MEL) can protect against oxidative damage under in vivo conditions, probably through its antioxidative capacity and ability to induce expression of anti-oxidative enzymes. The objective of this study was to investigate effects of diquat on viability of Vero and HeLa cells and possible protective effects of MEL and its analogue 2,3-dihydromelatonin (DMEL). Cell viability was evaluated with the MTT test. First, we analyzed dose-dependent effects of diquat on cell viability using the concentration range of 0.1-100 μM. Second, we used the diquat dose which reduced cell viability by 50% and treated cells with either MEL or DMEL (both in the concentration range of 1-100 μM) in the presence or absence of diquat. In addition, effects of both diquat and MEL on oxidative stress in HeLa cells were measured by flow cytometry using 2’,7’-dichlorofluorescin diacetate. We confirmed the expected negative effects of diquat on viability of Vero and HeLa cells. Melatonin and DMEL were able to prevent diquat reduced viability of Vero cells in rather low concentrations (1 μM) and DMEL exerted substantially stronger protective effects than MEL. However in HeLa cells, we did not find the same effects and MEL even reduced their viability. Moreover, treatment of HeLa cells with high concentrations of MEL (100 μM) exaggerated the pro-oxidative effects of diquat. The results suggest that in addition to the expected anti-oxidative effects, MEL exerts a pro-oxidative action which is cell type and dose dependent
Apoprotein(A) Isoforms Risk Factors for Atherogenesis in Esrd Patients on Haemodialysis
Authors: Labudovic Danica , Tosheska-Trajkovska Katerina , Alabakovska Sonja
Published: March 2015

Introduction. End-stage renal disease (ESRD) patients undergoing hemodialysis are at an increased risk of arteriosclerotic vascular disease (ASVD). The increased risk is commonly attributed to the traditional risk factors related to ESRD. However, interest for more recent risk factors for ASVD, such as the level of lipoprotein(a) and its specific apoprotein(a) has been promoted. The aim of this paper is to determine whether apo(a) phenotype is a risk factor for arteriosclerotic vascular disease in ESRD patients who are on hemodialysis.

Methods. Apo(a) phenotypisation was performed by using the Western Blot Technique of blood samples from 96 end-stage renal disease patients who were undergoing hemodialysis, and from 100 healthy individuals.

Results. Frequency distribution of the basic apo(a) isoforms calculated by means of the χ2-test has shown that there was no significant statistical difference in distribution among patients on hemodialysis, and healthy carriers (χ2-0.36, p<0.548-for carriers of single apo(a) isoforms, (χ2-0.10, p<0.7545-for carriers of double apo(a) isoforms). The calculated relative risks have demonstrated that apo(a) phenotype was not a risk factor for ASVD in HD patients.

Conclusion. Based on the results obtained, it can be concluded that the apo(a) phenotype is not a risk factor for arteriosclerotic vascular disease in patients undergoing hemodialysis.
Comparison of the Responsiveness of the Long-Form and Simplified Stroke Rehabilitation Assessment of Movement: Group- and Individual-Level Analysis
Authors: Huang Yi-Jing , Chen Kuan-Lin , Chou Yeh-Tai , Hsueh I-Ping , Hou Chieh-Yi , Hsieh Ching-Lin
Published: March 2015

Background

The group-level responsiveness of the original, 30-item Stroke Rehabilitation Assessment of Movement measure (STREAM-30) is similar to that of the simplified STREAM (STREAM-15), even though the STREAM-30 has twice as many items as those of the STREAM-15.

Objective

The purpose of this study was to compare the responsiveness of the STREAM-30 and STREAM-15 at both group and individual levels in patients with stroke. For the latter level, the Rasch-calibrated 27-item STREAM (STREAM-27) was used because the individual-level indexes of the STREAM-30 could not be estimated.

Design

A repeated-measurements design was used. In total, 195 patients were assessed with the STREAM-30 at both admission and discharge.

Methods

The Rasch scores of the STREAM-27 and STREAM-15 were estimated from the participants' responses on the STREAM-30. We calculated the paired t-test value, effect size, and standardized response mean as the indexes of group-level responsiveness. The significance of change for each participant was estimated as the individual-level responsiveness index, and the paired t test and test of marginal homogeneity were used for individual-level comparisons between the STREAM-27 and STREAM-15.

Results

At the group level, the STREAM-30, STREAM-27, and STREAM-15 showed sufficient and comparable responsiveness. At the individual level, the STREAM-27 detected significantly more participants with significant improvement and fewer participants with no change or deterioration compared with the STREAM-15.

Limitations

Few patients with subacute stroke showed deterioration at discharge, so the abilities of the 2 measures to detect deterioration remain inconclusive.

Conclusions

The STREAM-27 detected more participants with significant recovery compared with the STREAM-15, although the group-level responsiveness of the 2 measures was the same. The STREAM-27 is recommended as an outcome measure to demonstrate the treatment effects of movement and mobility for patients with stroke.
Self-implementation or FDIs in Hydropower Development: A Dilemma
Authors: Manandhar Bhai Raja
Published: March 2015

Not available.DOI: http://dx.doi.org/10.3126/hn.v16i0.12210Hydro NepalJournal of water, energy and environmentIssue. 16, 2015,Page : 1-1Upload date: March 1, 2015
Utilizing India’s One Billion Dollar Line of Credit Budhi Gandaki, Mahakali III and Bridge over Mahakali – Projects Born and Bred at Singha Durbar?
Authors: Pun S. B.
Published: March 2015

When India’s Prime Minister Narendra Modi offered Nepal $1 billion USD line of credit in August 2014, many Nepalese believed this would be utilized to implement the stalled 6,480 MW Pancheshwar Multipurpose Project. During the September 1996 Mahakali Treaty ratification, the Pancheshwar Project was claimed to make the ‘sun rise from the west’ for Nepal! In fact, the joint press release of the two prime ministers did stress to ‘finalise the DPR of Pancheshwar Development Project and begin implementation of the Project within one year.’ However, it was reported that, India’s External Affairs Secretary, Ms. Sujata Mehta, visited Nepal in November2014 and ‘concluded the terms and conditions for the credit line.’ While there was no word on the Pancheshwar Multipurpose Project, the Budhi Gandaki Hydropower Project suddenly raised its head with the government’s own finance minister strongly justifying it. Similarly, the Mahakali III Irrigation Project from the Tanakpur Barrage and amulti-lane motorable bridge over Mahakali River were also identified as projects to be funded through the Indian line of credit. This article examines the background of these three projects (Budhi Gandaki, Mahakali III, and bridge over Mahakali) and questions whether they were truly born in Singha Durbar, or further away in Delhi.DOI: http://dx.doi.org/10.3126/hn.v16i0.12211HYDRO Nepal  Journal of Water Energy and EnvironmentIssue No: 16 January, 2015Page: 1-6Uploaded date: March 1, 2015
Estimating Tunnel Strain in Weak and Schistose Rock Mass under a State of in-situ Stress Anisotropy
Authors: Shrestha Pawan Kumar , Panthi Krishna Kanta
Published: March 2015

Tunnels excavated in weak and schistose rock mass below high overburden (rock cover) are prone to instability in the form of tunnel deformation. The deformation in the tunnel takes place to such an extent that it is irreversible and of significant magnitude, which is often known as tunnel squeezing. In order to limit such plastic deformation in tunnels, it is desirable that the response of the rock mass to induced stresses is known so that requirement of rock support can be estimated. Contrary to the assumption of uniform in-situ stresses made in analytical solutions for elasto-plastic analyses, large degree of stress anisotropy condition prevails in most tunnelling conditions. The effect of such anisotropic stress condition leads to varying degrees of deformations around the tunnel contour. Therefore, stress anisotropy is also an important factor that needs to be addressed to ensure a proper support design for tunnels. This paper discusses the inter-relationship among rock mass property, in-situ stresses including horizontal to vertical stress ratio, tunnel support pressure and deformation. The study is based on the tunnel cases from the Nepal Himalaya. Three completed tunnel projects were selected, where moderate to large tunnel deformations had been recorded. Long term deformation records were analyzed to assess time independent and time dependent deformations. Results of the analyses of the tunnels in weak and schistose rock mass at stress anisotropy states show that a good correlation among tunnel strain, rock mass shear modulus, support pressure, vertical stress and stress ratio of horizontal to vertical stresses exists. Moreover, the study also shows that significant amount of time dependent deformation can occur in such weak rock mass. Such deformation was found to be high in schist and micaceous phyllite, moderate in graphitic phyllite and low in siliceous phyllite. The suggested relationships can be used as a basis for an early estimate of instantaneous and final deformations and the corresponding requirement of support pressures in tunnel walls in weak and schistose rock mass.DOI: http://dx.doi.org/10.3126/hn.v16i0.12212HYDRO Nepal  Journal of Water Energy and EnvironmentIssue. 16, 2015 January Page: 7-13 Upload date: March 1, 2015
The Case of Upper Karnali Hydroelectric Project
Authors: Shrestha Hari Man
Published: March 2015

The Upper Karnali Hydroelectric Project, being one of the most attractive and suitable run-of-river hydropower projects for consumption of the energy in Nepal, should have been developed by Nepal for self consumption through self-construction and self-financing. The author describes that in Nepal things are not happening in a way to safeguard Nepal’s long-term national interest through deriving multiple benefits from modest and gradual way of utilization of better hydropower sites for own sake. Even the meager free entitlements are highly exaggerated in a falsified way to please India instead of striving hard for fulfilling its own need by own efforts.DOI: http://dx.doi.org/10.3126/hn.v16i0.12213  HYDRO Nepal  Journal of Water Energy and EnvironmentIssue. 16, 2015 January Page: 14-17 Upload date: March 1, 2015
Analysis of Sediment Samples and Erosion Potential: A Case Study of Upper Tamakoshi Hydroelectric Project
Authors: Koirala Ravi , Chitrakar Sailesh , Regmi Surya Nath , Khadka Manisha , Neopane Hari Prasad , Thapa Bhola
Published: March 2015

Hydropower can be an effective green solution for meeting the current energy demand in Nepal. However, despite having tremendous water resources, only 2% of Nepal’s hydroelectricity potential has been tapped. Of the challenges that Nepali hydro faces, sediment erosion is a major one. Sediment erosion refers to an erosive tendency of sediment particles flowing with water over the exposed turbine parts including the runner. This paper deals with a sample analysis of sediment particles from the Upper Tamakoshi Hydroelectric Project. In this paper, we test for particle size distribution, particle count, mineral composition, and erosion potential analysis. For the mineral and erosion potential analysis, the sand samples range from 75 ìm to 200 ìm because the Tamakoshi plant consists of sediment traping system for particles larger than 150 ìm. The sediment samples were collected from three different points in the headrace and the severity of the effect of erosion has been analyzed in terms of depending variables like particle size, concentration, and mineral composition.DOI: http://dx.doi.org/10.3126/hn.v16i0.12216     HYDRO Nepal  Journal of Water Energy and EnvironmentIssue. 16, 2015, January Page: 28-31 Upload date: March 1, 2015
FDI in Hydropower and Choice of Jurisdiction
Authors: Shrestha Ratna Sansar
Published: March 2015

Not Available.DOI: http://dx.doi.org/10.3126/hn.v16i0.12219      HYDRO Nepal  Journal of Water Energy and EnvironmentIssue. 16, 2015, January Page: 32-33 Upload date: March 1, 2015
Study of Climate Change using GCM Downscaling: Special Reference to Indian Subcontinent
Authors: Gautam Narayan P. , Arora Manohar
Published: March 2015

Climate change refers to a change in a state of the climate and it is one of the emerging issues in the 21st century. General Circulation Model (GCM) represents physical processes in the atmosphere, ocean, cryosphere and land surface. It is one of the advanced tools for simulating the response of the global climate system to increasing greenhouse gas (GHG) concentrations. The application of GCMs and its downscaling outputs helps to fill up the gap existing between large-scale and local-scale variables. This study clearly showed that GCM downscaling has been increasingly applied to the study of climate change in many parts of the world including the Indian sub-continent and their results are utilized to enhance planning and management purposes. DOI: http://dx.doi.org/10.3126/hn.v16i0.12222         HYDRO Nepal  Journal of Water Energy and Environment Issue. 16, 2015, January Page: 36-39 Upload date: March 1, 2015
Cost-Effective and Eco-Friendly Methods for Lake Water- Purification
Authors: Dixit Savita , Dixit Shlok
Published: March 2015

Lakes and reservoirs are very important property for people’s life, industrial activities and so on. They provide various benefits to us, such as securing water resources for drinking, agriculture and industrial use, fishery resource, flood control functions and ecosystem integrities. However, because of the closed nature of lakes’ water system, pollution tends to accumulate therein, once water is polluted, it is difficult to improve the water quality. In Addition, the situation is that a remarkable improving tendency of the water quality of lakes is not seen due to the increase of the pollutant load by the economic change and the increase of the Industrialization and population as well as the change in the lake environment. Bhopal city popularly known as the city of lakes, have more than eighteen water bodies. Out of eighteen water bodies, few are source of drinking water after preliminary treatment. Rest of the water bodies serves secondary purposes like irrigation, fisheries and recreational activities etc. These two lakes are Shahpura Lakeand Lower Lake. Shahpura Lake is situated in new Bhopal city where as Lower Lake is situated in old city. Both are eutrophic and sewage fed lake. DOI: http://dx.doi.org/10.3126/hn.v16i0.12223          HYDRO Nepal  Journal of Water Energy and Environment Issue. 16, 2015, January Page: 40-43 Upload date: March 1, 2015
Combination of Francis and Pelton Turbines on a Pressure Pipe Line for an Optimal Utilization of Highly Variable Water Volumes
Authors: Sageder Thomas
Published: March 2015

Not Available.DOI: http://dx.doi.org/10.3126/hn.v16i0.12224           HYDRO Nepal  Journal of Water Energy and Environment Issue. 16, 2015, January Page: 44-45 Upload date: March 1, 2015
Evaluation of the 2010 Highway Capacity Manual Urban Street Free-Flow Speed Prediction Model
Authors: Moses Ren , Mtoi Enock T. , Ozguven Eren E.
Published: March 2015

The performance of the new 2010 Highway Capacity Manual (HCM 2010) procedure that predicts free-flow speed by using posted speed limit and eight additional variables was evaluated. The eight additional variables were the proportion of segment length with restrictive median, the proportion of segment with curb on the right-hand side, the number of access point approaches on the right side in the subject direction of travel, the number of access point approaches on the right side in the opposing direction of travel, the segment length, the width of the signalized intersection, the number of through lanes, and the distance between intersections. Multiday speed data from 104 Florida urban street segments with a speed limit ranging from 25 to 55 mph were used in the study. Field mean free-flow speed was determined for each analysis segment as well as the geometric and traffic attributes required by HCM 2010 to predict free-flow speed. Statistical and graphical analyses showed that the HCM 2010 speed prediction methodology had a low coefficient of determination and underpredicted free-flow speed when the segment posted speed limit was 35 mph or higher. The results further showed that the use of free-flow speed (predicted by the HCM 2010 methodology) in determining arterial level of service produced lower levels of service for 10 of the 20 segments analyzed. In addition, calibration of the HCM 2010 model coefficients showed that speed prediction by this model could be improved if the speed limit coefficient were doubled and that the influence of cross section and access density factors substantially decreased.
Comparison of Estimates of Travel Time Losses on High-Capacity Roads
Authors: Jäggi Boris , Hohmann Sandra , Axhausen Kay W. , Geistefeldt Justin
Published: March 2015

This paper compares two approaches to estimating travel time losses on freeways that are based on a whole-year analysis. Both approaches are intended to improve the design process for freeways by accounting for the annual traffic demand profile as well as short time variance of demand and capacity. One approach estimates breakdown probability and delay-related time losses by using a probabilistic model. The other approach uses Monte Carlo simulation to estimate travel time losses at freeway bottlenecks on the basis of a queuing model with stochastic demand and capacity. Both approaches are based on annual hourly demand profiles. The approaches are compared for demand profiles and deliver similar but not equal results. Travel time losses for both approaches increase exponentially with traffic volume, with the simulation-based approach consistently generating higher time losses for higher traffic volumes. Both approaches are a substantial improvement on current design procedures, are easy to apply, and are recommended for adoption in traffic analysis guidelines.
New Methodology to Determine Work Zone Capacity Distribution
Authors: Weng Jinxian , Yan Xuedong
Published: March 2015

Because the true value of work zone capacity is difficult to know with perfect confidence, work zone capacity should be represented by means of a probability distribution. This study proposes a methodology for determining work zone capacity distribution on the basis of the probabilistic speed–flow relationships. First, traffic speed and flow are modeled as random variables following the lognormal distribution. Then, the lognormal distributed speed–flow functions are established to formulize the probabilistic speed–flow relationships under uncongested and congested traffic conditions, respectively. Finally, a work zone capacity distribution model is derived on the basis of the probabilistic speed–flow relationships. A case study that uses the observed traffic data from Singapore work zones is conducted to confirm the effectiveness of the proposed methodology. The effects related to work zone configuration such as geometrical alignment and speed limit on the mean and prediction interval of work zone capacity are examined. The proposed methodology could help traffic engineers evaluate the variability of work zone capacity and the reliability of traffic management strategies.
Impact of Modeling Parameters on the Highway Capacity Manual–Based Procedure to Estimate Reliability of Freeway Corridors
Authors: Hadi Mohammed , Xiao Yan , Hu Pei , Ramirez Amauris , Shabanian Shaghayegh
Published: March 2015

The recently completed SHRP 2 L08 project developed methods, guidance, and associated computational engines for incorporating travel time reliability into the Highway Capacity Manual (HCM) analyses. This paper presents an investigation of the use of these products to assess advanced traffic management strategies such as incident management and ramp metering. The paper examines the impacts of input parameters to the traffic flow model and of the scenario generation module incorporated as part of the computational engines of the HCM-based reliability estimation procedure of freeway facilities. The results from the calibration of the traffic flow model of the computational engine indicate that adjusting the capacity values to the measured values based on traffic detector data improves the system's ability to replicate real-world queues and travel times. The results show that the methods used to derive incident attributes in the computational engine affect reliability performance measures, particularly the 95th percentile travel time index and the misery index, which are indicators of the worst 5th percentile conditions on the corridor. The assessment based on modeling results indicates that incident management can significantly reduce the 95th percentile travel time index and the misery index. The assessment of ramp metering shows only a slight improvement in reliability, but this result may be because of the inability of the model to assess adaptive ramp metering, which is the main type of ramp metering in use.
Investigation of Saturation Flow on Shared Right-Turn Lane at Signalized Intersections
Authors: Chen Peng , Qi Hongsheng , Sun Jian
Published: March 2015

Saturation flow rate is regarded as one of the key parameters in estimating capacity and delay for the evaluation of performance at signalized intersections. In China, the saturation flow rates of shared right-turn lanes typically show large fluctuations because of the different departure characteristics of through and right-turning traffic, as well as complex interactions with pedestrians. This study addresses this complexity by proposing a four-stage saturation departure model based on an empirical analysis of discharge headways in shared lanes. The developed model reflects the stochastic nature of vehicle–pedestrian conflict and constructs the logical relationships between shared right-turn saturation flow and its various influencing factors, such as right-turn proportion, pedestrian demand, and the storage capacity of the right-turn radius. A comparison of observed saturation flow rates and estimates from the proposed model and the Highway Capacity Manual demonstrates the good performance of the proposed method. The manual, however, is found to underestimate the effect of pedestrian interference on performed saturation flow rates.
Estimating the Mean Critical Gap
Authors: Troutbeck R. J.
Published: March 2015

The estimation of the critical gap has been an issue since the 1970s, when gap acceptance was introduced to evaluate the capacity of unsignalized intersections. The critical gap is the shortest gap that a driver is assumed to accept. A driver's critical gap cannot be measured directly, and a number of techniques have been developed to estimate the mean critical gaps of a sample of drivers. This paper reviews the ability of the maximum likelihood technique and the probability equilibrium method to predict the mean and standard deviation of the critical gap with a simulation of 100 drivers, repeated 100 times for each flow condition. The maximum likelihood method gave consistent and unbiased estimates of the mean critical gap, whereas the probability equilibrium method had a significant bias that was dependent on the flow in the priority stream. Both methods were reasonably consistent, although the maximum likelihood method was slightly better. If drivers were inconsistent, again the maximum likelihood method was superior. A criticism leveled at the maximum likelihood method has been that a distribution of the critical gap has to be assumed. It was shown that this did not significantly affect the method's ability to predict the mean and standard deviation of the critical gaps. Finally, the maximum likelihood method can predict reasonable estimates with observations for 25 to 30 drivers. A spreadsheet procedure for using the maximum likelihood method is provided in this paper. The probability equilibrium method can be improved if the maximum rejected gaps are used.
Lane Utilization at Two-Lane Arterial Approaches to Double Crossover Diamond Interchanges
Authors: Yeom Chunho , Schroeder Bastian J. , Cunningham Christopher , Vaughan Christopher , Rouphail Nagui M. , Hummer Joseph E.
Published: March 2015

Double crossover diamond (DCD) interchanges, also known as diverging diamond interchanges, are popular and promising alternative interchanges that are increasingly being implemented nationwide. One unique feature of a DCD interchange is that through movements on the arterial road have to cross each other twice to complete their movements, while enabling left-turn movements from the arterial to the freeway to proceed without stopping at the downstream intersection. Consequently, interchanges with heavy left-turn movements are good candidates for DCD implementation. This unique feature of a DCD interchange means that there is a need to research lane utilization at the upstream approach intersection of DCD interchanges, as the lane use could be unbalanced. This unbalanced lane utilization could have a significant effect on operations at the first crossover and the interchange as a whole. This study examined lane utilization factors provided in the Highway Capacity Manual 2010 (HCM) for conventional diamond interchanges and found that they are not generally applicable to DCD interchanges. The study then proposed a lane utilization model calibrated with field data obtained at three DCD sites. The new model fit observed conditions at the DCD sites better than previously developed HCM factors. The model was then validated with three additional DCD interchanges, and validation results confirmed that the new model adequately predicted DCD lane utilization. The authors recommend that DCD interchange designers and analysts use the new model where it is applicable but also that more research be conducted to find lane utilization factors for other DCD configurations.
Developing Improved Truck Passenger Car Equivalent Values at Signalized Intersections
Authors: Skabardonis Alexander , Dowling Richard , Kiattikomol Vasin , Safi Chirag
Published: March 2015

This paper describes the methodology and findings for developing improved passenger car equivalent (PCE) factors for trucks at signalized intersections on the basis of field data and simulation modeling. The Highway Capacity Manual 2010 (HCM 2010) assumes a single PCE value of 2.00 for trucks at traffic signals. The proposed truck PCE values are sensitive to the proportion of trucks, truck type, and intersection's approach grade. It is recommended that the current HCM 2010 approach of computing the heavy vehicle and grade effects on saturation flow rates independently be replaced with a new combined heavy vehicle and grade adjustment factor that takes into account the synergistic effects of heavy vehicles combined with upgrades.
Dual-Route Distribution Strategy with Supply Chain Disruption
Authors: Hur Sung Ho , Kim Dong-Kyu , Kho Seung-Young , Lee Chungwon
Published: March 2015

Unexpected disruptions in the supply chain can directly and indirectly cause additional logistics costs because of delayed delivery. Previous studies have minimized the additional cost with a network design that used the concept of level of service and unit delay cost; however, in cases of disruption in a regional distribution center (RDC), companies commonly must secure a bypass through another RDC and pay more to use a faster transportation mode. The aim of this study is to develop a dual-route distribution strategy to minimize the logistics costs that stem from the disruption in the RDC. The model addressed in this study determines the RDC allocation and the freight dualization ratio to establish a bypass before a disruption occurs and to ensure the punctuality of delivery without losses due to late delivery. An application of the model uses an actual company's network data. The results of this application show that the dual-route distribution strategy can be more advantageous than a single-route distribution strategy. The model provides a theoretical basis for the use of the dual-route strategy to minimize the direct and indirect costs associated with the RDC disruption.
Transit Route Design Solved with Wireless Data Collection Algorithms
Authors: Rey David , Almi'ani Khaled , Viglas Anastasios , Libman Lavy , Waller S. Travis
Published: March 2015

The transit route network design problem and its variants, aiming for economically viable and efficient transit routes in urban areas, has been attracting many contributions in recent years and continues to be an active research field. This activity is mainly caused by the intractability of the underlying optimization problems in large-scale transportation networks, generally leading to the use of heuristic schemes to build good practical solutions. A relationship between the transit route network design problem and the problem of data collection in wireless sensor networks is presented, and an innovative solution approach is proposed based on a recently proposed algorithm in that domain. The original solution algorithm is adapted to urban transportation networks and tests are carried out on large-scale data sets on a single-route variant of the transit route network design problem. The results obtained show that the solution approach can be efficiently tuned to meet specific route design objectives and provide balanced solutions.
High-Speed Train Network Routing with Column Generation
Authors: Li Yihua , Miao Qing , Wang Xiubin Bruce
Published: March 2015

This paper is based on an award-winning rail scheduling project. It examines a high-speed train routing problem in which the trains are operated on a large network with sparse stations. The relatively long distance between train stations makes it unlikely to get a backup train unit in time when an operating train is out of service because of the need for maintenance. Therefore, regular maintenance is carefully incorporated into the base routing plan and is strictly enforced. An integrated path-based routing model is proposed here to design train routes and scheduling optimally. The objective is to cover the published trains and timetable with the least cost without violating operational rules and maintenance requirements. The scheduling for each operational cycle needs to be completed in a timely manner and be implementable in practice. A heuristic is proposed to solve the problem in a column generation framework. Numerical tests are conducted with operational data from the French National Railways. The test not only shows a significant cost savings but also indicates its efficiency in real-world applications.
Capacity Estimation in Support of Mesoscopic Simulation as Part of Dynamic Traffic Assignment Models
Authors: Shabanian Shaghayegh , Hadi Mohammed
Published: March 2015

Dynamic traffic assignment (DTA) is increasingly being considered to model advanced strategies. Capacity is a crucial parameter in the calibration of traffic flow models utilized as part of DTA modeling. The Highway Capacity Manual has been used as the authoritative source for defining and estimating capacity in the United States. With increased traffic detector data availability in recent years, it is now feasible to locally measure capacity at bottleneck spots with different methods. This study investigates the benefits and necessity of implementing DTA in the analysis of advanced strategies, such as managed lanes, and the importance of the calibration of the associated traffic model parameters. In this regard, the importance of coding capacity based on detector measurements in DTA tools is illustrated, particularly when there is evidence that the modeled corridor capacity is lower than estimates based on the Highway Capacity Manual. The shortcomings of utilizing the traffic flow model of static assignment tools for assessing managed lanes, even when the measured capacity values are coded, are also demonstrated; this drawback illustrates the need to utilize simulation-based DTA modeling for such assessments.
Modeling Network Growth with Scaling Laws in a Linear Monocentric City
Authors: Huang Jie , Connors Richard D. , Maher Mike J.
Published: March 2015

Scaling relationships have been observed across urban systems and appear to reveal global emergent properties that may help to characterize, understand, and predict urban growth. Empirical urban studies that show scaling laws relating the growth in population to that of the transportation network warrant theoretical investigation. Such scaling phenomena are considered in the context of a linear monocentric city. Commuters are distributed from the city boundary to the common destination (the central business district), and two modes (railway and car) are available along the corridor. Two scenarios of urban growth are considered: vertical and horizontal. Road capacity and corridor length both increase alongside the population growth. Within these scenarios, growth is constrained to follow a scaling law and the evolution of network performance is examined. The results suggest that different long-term evolution trajectories may exist depending on the scaling-law and network features. On this basis, theoretical limits need to be investigated on the possible evolutionary pathways for a city whose growth is dependent on its transport system.
Modeling Corridor and Growth Pole Coevolution in Regional Transportation Network
Authors: Li Ye , Lu Danni , Tian Yuan
Published: March 2015

The relationship between the transportation network and the spatial layout of economic activity is fundamental theory to model the formation and expansion of transport corridors and cities in regional planning. However, previous efforts have mainly focused on the conceptual or theoretical model and failed to replicate the generation and development of corridors and cities in space. This study presents a mathematical model to describe the coevolution process of transport corridors and growth poles on a regional scale: from a few isolated cities and unconnected roads to a complex and interconnected urban system. The mathematical model has two major components: a corridor growth model and a growth pole formation model. The corridor growth model is characterized with network-flow adaption to reflect the cost convergence and flow expansion effect in a transportation network. The growth pole formation model embodies the pole–axis coevolution process based on the Steiner point identification using the index of accessibility. A coevolution simulation is applied to replicate how the growth poles and transport corridors emerged and evolved in the Yangtze River Delta region in China. Meanwhile, the rationality and feasibility of the model are validated. The results show that the presented model simulates well the development of transport corridors and growth poles in the Yangtze River Delta region.
The accuracy of linear indices of ventricular volume in pediatric hydrocephalus: technical note
Authors: Ragan Dustin K. , Cerqua Jonathon , Nash Tiffany , McKinstry Robert C. , Shimony Joshua S. , Jones Blaise V. , Mangano Francesco T. , Holland Scott K. , Yuan Weihong , Limbrick David D.
Published: March 2015

Assessment of ventricular size is essential in clinical management of hydrocephalus and other neurological disorders. At present, ventricular size is assessed using indices derived from the dimensions of the ventricles rather than the actual volumes. In a population of 22 children with congenital hydrocephalus and 22 controls, the authors evaluated the relationship between ventricular volume and linear indices in common use, such as the frontooccipital horn ratio, Evans' index, and the bicaudate index. Ventricular volume was measured on high-resolution anatomical MR images. The frontooccipital horn ratio was found to have a stronger correlation with both absolute and relative ventricular volume than other indices. Further analysis of the brain volumes found that congenital hydrocephalus produced a negligible decrease in the volume of the brain parenchyma.
Neurosurgery Education and Development program to treat hydrocephalus and to develop neurosurgery in Africa using mobile neuroendoscopic training
Authors: Piquer José , Qureshi Mubashir Mahmood , Young Paul H. , Dempsey Robert J.
Published: March 2015

OBJECT

A shortage of neurosurgeons and a lack of knowledge of neuroendoscopic management of hydrocephalus limits modern care in sub-Saharan Africa. Hence, a mobile teaching project for endoscopic third ventriculostomy (ETV) procedures and a subsequent program to develop neurosurgery as a permanent specialty in Kenya and Zanzibar were created and sponsored by the Neurosurgery Education and Development (NED) Foundation and the Foundation for International Education in Neurological Surgery. The objective of this work was to evaluate the results of surgical training and medical care in both projects from 2006 to 2013.

METHODS

Two portable neuroendoscopy systems were purchased and a total of 38 ETV workshops were organized in 21 hospitals in 7 different countries. Additionally, 49 medical expeditions were dispatched to the Coast General Hospital in Mombasa, Kenya, and to the Mnazi Moja Hospital in Zanzibar.

RESULTS

From the first project, a total of 376 infants with hydrocephalus received surgery. Six-month follow-up was achieved in 22%. In those who received follow-up, ETV efficacy was 51%. The best success rates were achieved with patients 1 year of age or older with aqueductal stenosis (73%). The main causes of hydrocephalus were infection (56%) and spina bifida (23%). The mobile education program interacted with 72 local surgeons and 122 nurses who were trained in ETV procedures. The second project involved 49 volunteer neurosurgeons who performed a total of 360 nonhydrocephalus neurosurgical operations since 2009. Furthermore, an agreement with the local government was signed to create the Mnazi Mmoja NED Institute in Zanzibar.

CONCLUSIONS

Mobile endoscopic treatment of hydrocephalus in East Africa results in reasonable success rates and has also led to major developments in medicine, particularly in the development of neurosurgery specialty care sites.