bluuebunny/crossref_metadata_2025 huggingface dataset:
Drillstring Mechanics Model for Surveillance, Root Cause Analysis, and Mitigation of Torsional and Axial Vibrations
Authors: Ertas Deniz , Bailey Jeffrey R. , Wang Lei , Pastusek Paul E.
Published: January 2013

Vibrations have been identified as one of the most frequent and persistent performance limiters by limiting weight-on-bit, rate of penetration, or borehole quality even when they may be low enough not to cause damage to downhole tools and equipment.

A general purpose drillstring mechanics model has been developed to analyze axial and torsional vibrations in the frequency domain and provide vibration indices indicative of dysfunction in these modes. The model utilizes transfer matrices to solve for harmonic perturbations around a baseline solution obtained from a torque-and-drag type analysis, and accounts for effects of well path, tool joints, viscous damping due to the drilling fluid, surface boundary conditions, bit characteristics, and special vibration mitigation tools. The model supports workflows for real-time vibration surveillance as well as post-drill root cause analysis and well redesign. For example, real-time stick/slip severity monitoring is enabled using 1-second surface measurements. As a well redesign tool, a large number of design alternatives can be quickly evaluated to mitigate vibrations.

Case studies utilizing high-frequency surface/downhole drilling mechanics data validated the model and identified three types of torsional dysfunctions with distinct signatures and mitigators: Unstable Stick/Slip, an instability associated mostly with the lowest-frequency torsional resonance of the drillstring; Bit/Bottomhole Assembly (BHA) Stall, intermittent, sudden mechanical jamming at the bottom of the drillstring; and Synchronous Torsional Oscillation, the amplification of periodic excitations at torsional resonances of the drillstring. In one case study, the stick/slip surveillance tool was superior to realtime downhole measurements in lag time, bandwidth, and accuracy. In another case, the root cause of prevalent Unstable Stick/Slip was identified as velocity-weakening aggressiveness of the bit. Among redesign options using a topdrive controller tuned to damp out the lowest-frequency torsional resonance was deemed most effective. One such controller was evaluated in the field and was very effective at mitigating stick/slip in subsequent wells.
Microstructures and electrode performances of Mg50Ni(50-X)Pdx alloys
Authors: Santos Sydney , Castro José , Ticianelli Edson
Published: January 2013

Magnesium and several of its alloys can absorb large amounts of hydrogen. This feature is desirable for several technological applications such as solid state hydrogen storage tanks and anodes of nickel-metal hydride (Ni-MH) batteries. For the latter, Mg-Ni alloys are considered very promising due to their high discharge capacities. Conversely, the low stability of Mg-Ni alloys in alkaline electrolytes have hindered their practical use. In the present manuscript, the effects of palladium black addition on the structure and electrochemical properties of the Mg50Ni50 (in at.%) alloy were investigated. The studied ternary alloys have general composition of Mg50Ni(50-x)Pdx, with 0 ≤ x ≤ 5 (in at.%). These alloys were synthesized by mechanical alloying from pure elements. The alloy powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray absorption spectroscopy (XAS) while their electrode performances were evaluated by galvanostatic cycles of charge and discharge. The investigated alloys have multi-phase structures composed of amorphous and nanocrystalline phases, with nano-grain sizes of nearly 5 nm. Concerning the electrode performance, the best results were attained by the Mg50Ni47.5Pd2.5 alloy, which kept a high discharge capacity and improved the cycling stability.
Synthesis, reactions and antineoplastic activity of 3-(2-oxo-2H-chromen-3-yl)-2-oxo-2H,5H-pyrano[3,2-c]chromene derivatives
Authors: Gašparová Renata , Koiš Pavol , Lácová Margita , Kováčová Silvia , Boháč Andrej
Published: January 2013

The key 3-(2-oxo-2H-chromen-3-yl)-2-oxo-2H,5H-pyrano[3,2-c]chromen-5-yl acetates 3 were synthesized in high yields by cyclocondensation of 4-oxo-4H-chromen-3-carbaldehydes 1 with coumarin-3-acetic acids 2 under mild conditions. The reaction pathway involves aldol condensation and subsequent intramolecular lactonization to afford 2-oxo-2H,5H-pyrano[3,2-c]chromene skeleton 3. Further treatment of acetates 3 with alcohols, water or nitrogen containing compounds led to 5-alkoxy-, 5-hydroxy- or 5-acylamino-2H,5H-pyrano[3,2-c]chromen-2-ones 4-6 via nucleophilic substitution of acetyloxy group at C-5. Acetates and hydroxyl derivatives 3 and 5 undergo facile rearrangement in an acid medium yielding 5-hydroxypyrano[2,3-b]chromen-2(10aH)-ones 7.

Twelve prepared compounds were evaluated on their antineoplastic activities on 60 human tumour cell line panels in NCI USA. The obtained biological results confirmed that 3-(2-oxo-2H-chromen-3-yl)-2H,5H-pyrano[3,2-c]chromen-2-one represents a new leading skeleton suitable for further antitumour activity study.
Fullerenes patched by flowers
Authors: Pop Raluca , Medeleanu Mihai , Diudea Mircea , Szefler Beata , Cioslowski Jerzy
Published: January 2013

Stability measures, such as the total energy and the HOMO-LUMO gap, calculated at the Hartree-Fock and DFT levels of theory, and the aromatic character of five circulenes/flowers with a hexagonal core and petals consisting of 5-, 6- and 7-membered rings are investigated. Geometric (HOMA) and magnetic (NICS) criteria are used to estimate the local aromatic character of every ring of the investigated circulenes. The local aromaticity of the coronene and sumanene patches in two tetrahedrally spanned fullerenes were calculated and compared with the HOMA and NICS values of the corresponding isolated circulenes.
Spectrophotometric and voltammetric characterization of a novel selective electroactive chemosensor for Mg2+
Authors: Zor Erhan , Saf Ahmet , Bingol Haluk
Published: January 2013

A novel azocalix[4]arene derivative, 5,11,17,23-tetrakis[(acetophenone)azo]-25,26,27,28-tetrahydroxycalix[4]arene (APC4), containing acetophenone azo groups at the upper rim was synthesized as a chemosensor. Its binding and sensing properties with alkali and alkaline earth metal ions (Li+, Na+, K+, Rb+, Cs+, Mg2+, Ca2+, Sr2+, Ba2+) were investigated by UV-vis spectrophotometric and voltammetric techniques. The stoichiometric ratio and the association constant were determined spectrophotometrically as 1:1 and (1.94±0.31)×105 L mol−1 for the complex between Mg2+ and the chemosensor, respectively. Moreover, it was shown that the interaction between Mg2+ and the APC4 occurred by means of the phenol groups at the lower rim by voltammetric methods. The results of spectrophotometric and voltammetric experiments showed that the chromogenic chemosensor has high selectivity towards Mg2+ among the other used metal ions, especially the interfering Ca2+ ion.
Can Patients with Common Variable Immunodeficiency Have Allergic Rhinitis?
Authors: Agondi Rosana C. , Barros Myrthes T. , Kokron Cristina M. , Cohon Andrea , Oliveira Ana K.B. , Kalil Jorge , Giavina-Bianchi Pedro
Published: January 2013

Background

Rhinosinusitis is highly prevalent in patients with common variable immunodeficiency (CVID), and probably allergic rhinitis (AR) may be masked by a history of repeated respiratory infections. The diagnosis of AR is based on the patient's symptoms and detection of specific immunoglobulin E (IgE) to aeroallergens. This study was designed to identify rhinitis of probable allergic cause in patients with CVID.

Methods

This study included 72 adult CVID patients. The patients were divided into three groups according to their history: suggestive of AR, nonallergic rhinitis, and without rhinitis. They were tested for total and specific IgE (in vivo and in vitro).

Results

The patients’ mean age was 38.2 years. A history of chronic rhinitis was observed in 59 (81.9%) of the cases, 31 of which (43%) had a history suggestive of AR. Patients with a history of rhinitis (whether allergic or nonallergic) presented an earlier onset of symptoms and diagnosis of CVID. Total IgE was undetectable in 86.1% of patients. AR was confirmed by detection of specific IgE to aeroallergens in only 5.6% of the patients.

Conclusion

In CVID patients, chronic rhinitis may be allergic, because many have personal and family histories suggestive of atopy. However, in this study, allergy was confirmed by specific IgE detection in only 5.6% of cases. CVID patients with a history suggestive of AR commonly present negative results on traditional testing, so additional experiments may be necessary. One suggestion for the investigation of AR in CVID patients would be nasal provocation with the most prevalent allergens.
NCDs in Nepal: Burgeoning Burden amid Low Priority and the Ways Forward
Authors: Gautam R
Published: January 2013

DOI: http://dx.doi.org/10.3126/hprospect.v11i0.7420Health Prospect 2012 Vol.11
Unmet Need for Contraception and its Associated Factors among Married Women of Reproductive Age in Simichaur VDC of Gulmi District
Authors: Kandel NR
Published: January 2013

Background Nepal Demographic Heath Survey conducted in 2006, has indicated 26.4 percent of unmet need among married women of reproductive age had unmet need at national level. Unmet need for limiting was highest (15.2%) where as spacing method constitutes at 9.4 percent. At western region, the vary region where the Gulmi district is situated unmet need is 32.4 % with 36.6 % of married women of reproductive age currently using contraceptives is lower than at the national level (44.2%).The objective of the study was to find out the various factors associated with the unmet need for contraception among married women of reproductive age group in Simichaur VDC of Gulmi district Methods It was a descriptive, cross sectional, community based study. Altogether 131 married women of reproductive age were interviewed while the systematic random sampling method was designed for sampling procedure. Interview was done using semi-structured questionnaire for data collection. Results Among 131 Married women of reproductive age, 42 percent were found currently using modern contraceptive method. Forty eight percent of the married women of reproductive age had unmet need for contraception, 29.7 percent for limiting and 18.3 percent for spacing. Less than a half of the respondent (45.8 percent) were able to name all seven modern contraceptive methods with the correct information about their source Conclusion The unmet need for family planning was high and the major reason for non-use of contraception were absence of husband, fear of side effect and having no information about contraceptives. So, Program that focuses on correct information sharing about contraceptives with couple should be designed, communication and discussion about family planning between spouses, programs that encourage the involvement of men in family planning should be developed and implemented. DOI: http://dx.doi.org/10.3126/hprospect.v11i0.7423 Health Prospect 2012;11:11-14
Sexual Behaviour among Higher Secondary School Students of Kathmandu Metropolitan City
Authors: Khanal P
Published: January 2013

Background:Lack of knowledge and skills to avoid risky behaviour and lack of access to youth- friendly reproductive health information and services place young people in a position of great vulnerability.Adolescents are at the stage of experimentation and are easily influenced by their peers and are therefore a vulnerable population at risk for HIV/ AIDS and other STIs. Safe sexual behaviour has a crucial role in the prevention of problems related to sexual and reproductive health. The study was designed to explore the sexual behaviour among students of Higher Secondary School in Kathmandu Metropolitan City. Methods: The study was cross-sectional and a total of 268 students enrolled in 12th grade from 6 Higher Secondary Schools were involved in the data collection process. Data collection was done using anonymous, self-administered questionnaire Results: Among total 263 unmarried students, nearly onefifth (17.9%) students have ever had sexual contact. Study showed that nearly half of the sexually experienced students (46.8%) were involved in unsafe sexual behaviour. Conclusion: Nearly one-fifth students had premarital sex and nearly half of the students had been involved in unsafe sexual behavior. Based on the findings, the study recommends that the major concern should be on making the sexual relations safe and it is therefore necessary to encourage young people to be consistent condom users. DOI: http://dx.doi.org/10.3126/hprospect.v11i0.7424 Health Prospect 2012;11:15-18
Cost-effectiveness of models of care quality for children affected by HIV and AIDS in Nepal
Authors: Pradhan PM , Bhatta G , Bam K
Published: January 2013

Background: With an estimated sixty four thousand people living with HIV in Nepal, there are tremendous implications for children, whose lives are greatly affected when a parent is infected. The objective of this study is to identify and assess cost effectiveness for existing models of care for children affected with HIV/AIDS Methods: The study performed cost effective analysis for types of care and support for children affected by HIV and AIDS in Nepal from a societal perspective. Types of care and support to Children affected by HIV/AIDS were assessed, Comparator minimum was estimated based on government minimum standards guideline; comparative analysis for cost effectiveness was done in terms of care quality, and overall modes of care delivery. Results: This study identified only three types of care model (comprehensive institutional model of care, home based care and support, community based care with income generation) prevalent in Nepal. Out of this three types of models of care: Community based care with income generation was assessed as the most cost effective care model in Nepal. Conclusion: Community based care with income generation imparted children with better socialization and professional skills. However, continuum of care was often missed by one model, therefore other existing models of child care were also essential to provide care and provision of safety nets for children who fail to reach the care homes should also be considered by the government. DOI: http://dx.doi.org/10.3126/hprospect.v11i0.7425 Health Prospect 2012;11:19-25
Role of Medical Sociology and Anthropology in Public Health and Health System Development
Authors: Sigdel R
Published: January 2013

DOI: http://dx.doi.org/10.3126/hprospect.v11i0.7427 Health Prospect 2012;11:28-29
Malnutrition in Children: A Serious Public Health Issue in Nepal
Authors: Joshi PC
Published: January 2013

DOI: http://dx.doi.org/10.3126/hprospect.v11i0.7439 Health Prospect 2012;11:61-62
Opportunities in Integration of Family Planning in HIV/AIDS Services in Nepal
Authors: Mishra SR
Published: January 2013

DOI: http://dx.doi.org/10.3126/hprospect.v11i0.7440 Health Prospect 2012;11:63-64
Association between Mental Disorders and Suicide
Authors: Bista AB
Published: January 2013

DOI: http://dx.doi.org/10.3126/hprospect.v11i0.7441 Health Prospect 2012;11:66-66
Chemical Constituents of Yarsagumba (Ophiocordyceps sinensis (Berk.) Sung et al.), a Valued Traditional Himalayan Medicine
Authors: Shrestha Sabina , Shrestha Bhushan , Park Ji-Hae , Lee Dae-Young , Cho Jin-Gyeong , Baek Nam-In
Published: January 2013

Ophiocordyceps sinensis (Berk.) Sung et al. is popularly known as Yarsagumba (winter worm summer grass) in Nepal. It is a well-known entomogenous fungus distributed in alpine nival zone of trans-Himalayas and Tibetan Plateau. Its occurrence in extreme biological niche and cohabitation with insect [Thitarodes (Hepialus)] larvae has led to unique assemblage of metabolites including proteins and nitrogenous compounds, polysaccharides, sterols, nucleosides, fatty acids and their derivatives, vitamins and inorganics. In traditional Chinese medicine, it is one of the most trusted main ingredients for several preparations of remedy from wide range of human health conditions. Several biological activities from O. sinensis have been reported that include anti-inflammatory, antioxidant, antitumor, anti-metastatic, immunomodulatory, antimicrobial, insecticidal, hypolipidaemic, hypoglycemic, anti-ageing, lipolytic, neuroprotective, renoprotective effects, etc. The chemical constituents and their pharmacological uses are reviewed here highlighting the potentiality of this highly esteemed traditional Himalayan medicine. Nepal Journal of Science and Technology Vol. 13, No. 1 (2012) 43-58 DOI: http://dx.doi.org/10.3126/njst.v13i1.7398
Effect of Solvent Composition on the Critical Micelle Concentration of Cetylpyridinium Chloride in Ethanol-Water Mixed Solvent Media
Authors: Bhattarai Ajaya , Shah Sujit Kumar , Yadav Ashok Kumar
Published: January 2013

The accurate measurement of the specific conductivity of cetylpyridinium chloride in pure water and ethanol-water mixed solvent media containing 0.10, 0.20, 0.30 and 0.40 volume fraction of ethanol at room temperature are reported. The concentrations were varied from ~ 0.005 mol l-1 to ~ 0.0002 mol l-1.The conductivity of cetylpyridinium chloride decreases with the increase in the volume fraction of ethanol. The critical micelle concentration of cetylpyridinium chloride increases with the increase in the volume fraction of ethanol. Nepal Journal of Science and Technology Vol. 13, No. 1 (2012) 89-93 DOI: http://dx.doi.org/10.3126/njst.v13i1.7446
Physico-chemical Characterization of Gosainkunda Lake
Authors: Raut Rosha , Sharma Subodh , Bajracharya Rosha M , Sharma Chhatra Mani , Gurung Smriti
Published: January 2013

High altitude lakes are very sensitive to climate change due to their small catchment area, limited vegetation cover, surface water with low nutrients, and thin soil and low bedrock weathering rates. The present study was focused on high altitude Himalayan Lake Gosainkunda, situated at an elevation of 4300 m in the Langtang National Park, and carried out during the post- monsoon season (October) in 2010. The main aim of the study was to assess the water quality quantitatively considering the anthropogenic as well as natural impacts in the lake. The water samples were collected at six different sites to represent entirely the quality of the lake. The sampling sites were systematically designated as the inlet, outlet, human influence site, littoral zone, middle (central) and the deepest part of the lake. Some major cations (Ca++, Mg++, Na+ & K+) and anions (Cl-, SO4 — & HCO3 -) were analyzed; the cation type is dominated by Ca++ (64%) while the anions are dominated by Cl- (49%). Among the trace elements (Al, Fe, Mn, Zn, Cu, Cd, Cr, Ni, Pb & As), except for Al and Fe, all others were found below the detection limit. Nepal Journal of Science and Technology Vol. 13, No. 1 (2012) 107-114 DOI: http://dx.doi.org/10.3126/njst.v13i1.7449
Multi-Drug Resistant Bacterial Strains in Lower Respiratory Tract Infections, Antibiotic Sensitivity Patterns and Risk Factors
Authors: Sherchan Jatan B , Gurung Pranita , Bam Dirgh Singh , Sherchand Jeevan Bahadur
Published: January 2013

Isolation of multidrug resistant bacteria such as extended spectrum beta-lactamase (ESBL), metallo beta–lactamase (MBL) producing and Methicillin resistant Staphylococcus aureus (MRSA) causing lower respiratory tract infection (LRTI) is associated with various risk factors and a major challenge in treatment. So, the study determined bacterial etiology of lower respiratory tract infection and antibiotic sensitivity pattern with special reference to ESBL, MBL, and MRSA strains along with risk factors associated with such strains. A total of 120 specimens were collected from patients with lower respiratory tract infection along with clinical details. Combination disk method was done for the detection of ESBL and MBL producing isolates and oxacillin disc was used to detect MRSA. Out of 120 specimens, 87.5% was monomicrobial while 12.5% was polymicrobial infection. Pseudomonas aeruginosa (36.19%) was the predominant followed by Acinetobacter baumannii (28.57%), Klebsiella pneumoniae (20.95%), Escherichia coli (8.57%) and Staphylococcus aureus (5.72%). Total 33 (31.43%) out of 105 monomicrobial isolate were MDR. All MDR E. coli, K. pneumoniae, P. aeruginosa were ESBL producers and (6, 20%) out of total A. baumannii isolated produced MBL and was not found to produce ESBL. All MDR S. aureus isolates were found to be resistant to methicillin. Carbapenems followed by amikacin were found to be the most effective antibiotic for Gram negative bacilli causing LRTI. Vancomycin, Teicoplanin & Linezolid were found to be the most effective antibiotics for MRSA. 28 out of 33 MDR isolate possessing patients had comorbid illness. Isolation of MRSA, ESBL and MBL producing bacteria in LRTI are increasing in number. Increased prevalence of MDR bacterial strains form patients with comorbid illness is a major problem in healthcare centers. Nepal Journal of Science and Technology Vol. 13, No. 1 (2012) 157-163 DOI: http://dx.doi.org/10.3126/njst.v13i1.7454
Cholera, Shigellosis and Salmonellosis Incidence Among the People of some Districts of Nepal
Authors: Shah Binod Kumar , Sharma Sapana , Shakya Gita , Upadhyay Bishnu Prasad
Published: January 2013

Diarrhoea is a major health problem throughout the world, and responsible for high morbidity and mortality in Nepal. The cross-sectional prospective study was carried out to determine the incidence of Cholera, Shigellosis and Salmonellosis with screening of possible extended spectrum â-lactamase producers from 268 diarrhoeal stool samples from Nepalgunj area and different hospitals of Nepal during April 2010 to January 2011. The specimens were processed by standard microbiological methods and the casual organisms confirmed with serology. Altogether 14.18% of bacterial incidence was found with 8.21% incidence of Vibrio cholerae O1, 2.24% of Shigella spp. and 3.73% of Salmonella spp. All isolated Vibrio cholerae O1 were El Tor Ogawa and all Shigella spp. were Shigella flexneri B. Highest bacterial culture positivity (47.36%) were observed in Kathmandu while highest V. cholerae isolation (77.27%) was observed in Nepalgunj. The highest number of Salmonella spp. and Shigella spp. were isolated from Kanti Children’s Hospital. Highest bacterial culture positivity (47.36%) and highest isolation of V. cholerae (81.81%) were observed in August. The bacterial culture positivity was significantly associated with places and months (p <0.05). However, there was no statistical difference in the bacterial culture positivity with sex (P >0.05). 100% Vibrio cholerae, 100% Shigella spp. and 80% Salmonella spp. were multi-drug resistant. Only one Salmonella Cholerasuis was extended spectrum â-lactamase producer. Nepal Journal of Science and Technology Vol. 13, No. 1 (2012) 165-172 DOI: http://dx.doi.org/10.3126/njst.v13i1.7455
Assessment of Microbial Quality of Chlorinated Drinking Tap Water and Susceptibility of Gram Negative Bacterial Isolates Towards Chlorine
Authors: Bishankha Suraj , Joshi Tista Prasai , Joshi Dev Raj , Bhatta Dwij Raj
Published: January 2013

Sixty (56.1%) water samples crossed the permissible limit of WHO guideline value in heterotrophic plate count and total coliform count each. Ten different genera of gram negative bacteria were recovered in which E. coli was predominant followed by Citrobacter spp., Shigella spp., Enterobacter spp., Providencia spp., Klebsiella spp., Salmonella spp., Pseudomonas spp., Proteus spp. and Edwardsiella spp. Higher the temperature of water sample, higher the bacterial growth was obtained (p= 0.002), and similarly higher level of free residual chlorine in water reduced the bacterial growth (p= 0.037) whereas increase or decrease of pH (p= 0.454), turbidity (p= 0.164) and conductivity (p= 0.969) did not affect the microbial growth. A negative correlation (r= -0.162) between heterotrophic plate count and free residual chlorine was observed, however, without statistical significance (p= 0.096). Similarly, a negative correlation (r= -0.383) between total Coliform count and free residual chlorine was observed with statistical significance (p= 0.001). In chlorine assay, all tested eight genera of gram negative bacteria were found to be chlorine resistant at 0.2 mg/l for a contact time of 30 minutes. Average time required for T99.9 (3-log) and T99.99 (4-log) reduction of viable isolates from initial population of 2×106 cells/ml were found to be less than 30 minutes and greater than 60 minutes respectively. Log inactivation of various bacterial isolates with chlorine concentration of 0.2 mg/l for a contact time of 30 minutes were found to be ranged from 3 to 3.5-log. Emergence of chlorine resistant organisms in drinking water probably demands alternate disinfection or mitigation strategy. Nepal Journal of Science and Technology Vol. 13, No. 1 (2012) 173-178 DOI: http://dx.doi.org/10.3126/njst.v13i1.7456
Absorption Spectra of Natural Dyes and Their Effect on Efficiency of ZnO Based Dye-Sensitized Solar Cells
Authors: Karki IB , Nakarmi JJ , Mandal PK , Chatterjee S
Published: January 2013

Natural dye-sensitized solar cells (DSSC) are one of the most promising devices for the solar energy conversion due to their low production cost and low environmental impact. The synthesis and performance study of Zinc oxide (ZnO) nanorods based DSSC is reported in the present paper. ZnO nanorods were fabricated using sol-gel spin coating process and different types of DSSCs were fabricated using two different classes of natural dyes, xanthenes, anthocyanins and a mixed-dye with equal proportion mixture of xanthenes and anthocyanins. The ultravioletvisible (UV-Vis.) absorbance spectra were compared with performances of the cells. Efficiency of fabricated cells and cell characteristics were found to be related with absorption spectra of dyes. Nepal Journal of Science and Technology Vol. 13, No. 1 (2012) 179-185 DOI: http://dx.doi.org/10.3126/njst.v13i1.7457
Development of Surveys for Study of Departure Time Choice: Two-Stage Approach to Efficient Design
Authors: Arellana Julián , Daly Andrew , Hess Stephane , de Dios Ortúzar Juan , Rizzi Luis Ignacio
Published: January 2013

Modeling of departure time choice has recently received renewed attention because of the increasing levels of congestion in many cities and the growing popularity of travel demand management strategies such as road pricing. Current practice for evaluation of the effectiveness of travel demand management policies usually involves incorporation of the temporal dimension into transport planning models only through fixed factors derived from origin–destination data, but this practice makes them unsuitable for use in proper prediction of demand at different times of the day. To mitigate these deficiencies, the authors argue in favor of estimation and application of specially formulated time-of-day choice models. Here the concentration is on the process used to generate a survey design that obtains data suitable for estimation of such models that will ensure both realism and simplicity in the presentation; in particular, the stated preference exercise includes dependence between attribute levels. The proposed procedure should be widely applicable and offers many improvements over current practice in the field.
Sustainable and Healthy Travel Choices and the Built Environment: Analyses of Green and Active Access to Rail Transit Stations along Individual Corridors
Authors: Appleyard Bruce
Published: January 2013

Until recently, data and technology have limited the ability of travel behavior research to uniquely capture details of the built environment that may influence a person's choice to walk or bicycle. Most previous studies have relied on aggregated zonal averages homogeneously attributed to unique individuals and have likely missed key subtleties of the built environment important to people traveling outside the protective enclosure of an automobile. Furthermore, most studies focus on the characteristics of the origin, not the critical components of the destination (such as parking, availability, and price). To understand better the choice of green and active modes, which is central to an understanding of how to achieve important environmental and health benefits, this paper presents methods to align detailed measures of the built environment (in sum, more finely disaggregated data of the built environment) more closely with the individual for disaggregated analyses of travel behavior. Through the use of a new, linear spatial unit of analysis—the individual access corridor—characteristics of the built environment are captured all the way from the origin to the destination for a group of individuals large enough to be statistically meaningful for policy and urban design guidance through the use of predictive, multinomial logit mode choice models. This study provides planning and design guidance on how to increase the likelihood that one will choose walking or bicycling over motorized modes and examines such elements as zoning, subdivision ordinances, and streetscape design as well as station policies for bicycle and auto parking.
Comparison of Four-Step versus Tour-Based Models for Prediction of Travel Behavior before and after Transportation System Changes
Authors: Ferdous Nazneen , Vana Lakshmi , Bowman John L. , Pendyala Ram M. , Giaimo Gregory , Bhat Chandra R. , Schmitt David , Bradley Mark , Anderson Rebekah
Published: January 2013

The main objective of this study was to examine the performance of the Mid-Ohio Regional Planning Commission trip-based and tour-based frameworks in the context of three specific projects started and completed within the past 20 years in the Columbus, Ohio, metropolitan area. Region- and project-level comparisons of the performance of the trip- and tour-based models were made for three scenario years: 1990, 2000, and 2005. The region-level analysis was undertaken in the context of four travel dimensions on the basis of data availability and observed data to model output compatibility. These four dimensions were vehicle ownership, work flow distribution, work flow distribution by time of day, and average work trip travel time. The tour-based model performed better overall than the trip-based model for all four dimensions. The project-level comparative assessment of the predicted link volumes from the trip-based and the tour-based models was undertaken according to the observed link counts and roadway functional class. The results did not show any clear trends according to the performance of the models by functional class or year.
Estimating Mobile-Source Greenhouse Gas Emissions in Los Angeles County, California: Web-Based Tool for Calculation of Benefits of Transportation Improvement Projects for Reduced Emissions
Authors: Jackson David , Snavely Michael , Calix Robert , Indrakanti Suseel
Published: January 2013

California's Sustainable Communities and Climate Protection Act of 2008 (Senate Bill 375, enacted in 2008) requires jurisdictions to identify changes to policies and systems to reduce mobile source greenhouse gas (GHG) emissions. As a result, local public officials and planners need flexible tools beyond traditional travel demand models to estimate the impacts of transportation policy and investment decisions on carbon emissions. Although several tools and calculators offer high-level estimates of reductions in GHG emissions in multiple sectors, the available tools and calculations generally lack local contexts and sensitivities, which are the primary drivers of the potential to reduce GHG emissions at the project level. Given this analytic need, the Los Angeles County Metropolitan Transportation Authority (LACMTA), California, recognized the connection between the data estimation needs of the legislation and the existing calculation capabilities of the web-based platform for its congestion mitigation fee program. The agency partnered with Cambridge Systematics to develop a tool to estimate the project-level impacts on the carbon emissions of a diverse range of local projects included in the congestion mitigation fee program. The tools for sketch planning developed for LACMTA offer easy data entry, a transparent framework, a web-accessible interface, and immediate reporting of results while remaining sensitive to local conditions. The tool's accessible design was central to its successful use in the development of the sustainable communities strategy of the Gateway Cities Council of Governments. This paper presents the policy context that guided tool development; highlights of the development process and methodology; a summary of the testing, delivery, and application of the sustainable communities strategy of the Gateway Cities Council of Governments; and a view of the tool's limitations and opportunity for enhancements.
Trip Rates and Accessibility: Gleaning Basic Planning Information from Activity-Based Travel Demand Model
Authors: Wu Daniel , Sall Elizabeth , Newhouse Stephen
Published: January 2013

Planners have developed an appetite for complex and multifarious models to match the intricacy of the questions being asked. For the most part, these new models, such as the currently popular activity-based modeling framework, are seamlessly backward compatible with all the previous questions that planners still ask from time to time. However, a seemingly simple question was recently raised in San Francisco, California, and the San Francisco County Transportation Authority's advanced, state-of-the-art activity-based model SF-CHAMP (San Francisco Chained Activity Modeling Process) was not equipped to handle it gracefully. This paper documents a methodology used to create a schedule of the auto trip rates from the SF-CHAMP activity-based travel demand model. The linear regression methodology uses outputs from the SF-CHAMP model along with simple accessibility variables to account for the wide variations in vehicle trip rates across the city and to provide a nexus between trip generation rates and the context of their origins or destinations. This approach combines the desired simplicity of auto trip generation rates in the local context of San Francisco and sensitivity to a set of accessibility variables comprehensible to humans.
Quantitative Approaches for Project Prioritization: Case Study in Puget Sound, Washington
Authors: Outwater Maren L. , Adler Thomas , Dumont Jeffrey , Kitchen Matthew , Bassok Alon
Published: January 2013

Transportation projects in major metropolitan regions can vary widely in the types of benefits that they provide and in the scales of those benefits. Travel forecasting models and related procedures can provide reasonable estimates of those benefits, and many benefits can be distilled into equivalent monetary benefits by the use of consumer surplus or other valuation approaches. In theory, those methods could also be used to prioritize projects for funding consideration. However, an approach that simply chooses projects that provide the greatest net economic benefits may not result in a mix of projects that most effectively accomplishes broad regional goals. This paper describes an approach to project prioritization that was developed to support stakeholder-based weighting of multiple goals and, for each goal, multiple measures. The approach uses the analytic hierarchy approach to develop weights for each goal and a conjoint-based method to estimate stakeholder weights for each measure. The approach was applied as part of Washington State's Puget Sound Regional Council's Transportation 2040 process and achieved the goals in VISION 2040, the long-range land use plan. Weighting exercises were conducted with two stakeholder groups, and the results were applied to a set of proposed ferry, rail, highway, and local road projects. This paper describes the details of this case study and provides observations and conclusions from the work. The principal findings of the experiments were that statistically robust modeling conducted in real time during planning committee meetings can improve the transparency, equity, and collaboration of the project prioritization process.
Practical Guidelines for Estimation of Rest Area Use on Rural Interstates and Arterial Highways
Authors: Al-Kaisy Ahmed , Veneziano David , Kirkemo Zachary , Dorrington Christopher
Published: January 2013

Rest areas perform a critical role in the highway network. These areas provide passenger vehicle occupants and heavy vehicle operators with an opportunity to use a restroom, walk around, stop for a meal, sleep for a period of time, or even pause to use a cellular phone. These activities also have a direct impact on the various aspects of rest area planning and design. Existing guidance for rest area planning and design is largely based on national trends, which may not represent patterns of use in rural states. This paper presents a series of practical guidelines that may be used in the design and rehabilitation of rest area facilities, particularly those in rural areas. The guidance was developed by the use of empirical observations of rest area use at 44 study sites in the state of Montana. Given the amount of data collected and used in this research, it is reasonable to expect that the guidelines developed are representative of a significant proportion of existing and future rest area sites in rural locales. However, each rest area is different, and careful consideration should be given when the guidelines outlined in this paper are used.
Comparison of Time-Dependent Sequential Logit and Nested Logit for Modeling Hurricane Evacuation Demand
Authors: Gudishala Ravindra , Wilmot Chester
Published: January 2013

Models that predict hurricane evacuation demand can play a crucial role in developing and evaluating alternative evacuation policies and plans. However, to evaluate alternative policies effectively, evacuation demand models should be sensitive to time varying characteristics of a storm and the contextual conditions surrounding an evacuee. The time-dependent sequential logit is one such model, but it makes use of restrictive assumptions about the dynamic choices made by evacuees. A new model, a time-dependent nested logit model, relaxes those assumptions. It was formulated and derived in this study, and its performance was then compared with that of the time-dependent sequential logit model by applying both models to data from Hurricane Gustav. The results indicated that the time-dependent nested logit model has better predictive capability than the time-dependent sequential logit model.
Evacuee Route Choice Decisions in a Dynamic Hurricane Evacuation Context
Authors: Robinson R. Michael , Khattak Asad
Published: January 2013

Very high traffic volumes may lead to extensive congestion during hurricane evacuations. Evacuation planners reduce this congestion by careful planning for multiple hurricane scenarios and assignment of evacuation routes and timing. This planning may be for naught if obstructions block key roadways. An advanced traveler information system (ATIS) may be used to guide evacuees to alternate routes, but how effective will that guidance be? Should the use of alternate routes be encouraged? How are drivers likely to respond to delays and information? Will information shorten or improve the reliability of travel times in emergency conditions? Integration of a dynamic evacuation simulation and a decision-making model (representative of the decisions made by potential hurricane evacuees when provided with information on downstream traffic congestion and alternate routes) can help emergency planners prepare for the unexpected. Advance modeling of likely accident locations and the severity can forecast the effects of alternate route use, help determine the best locations and timing of alternate route information, and support decision making. This study integrated an evacuee route choice decision model and a mesoscopic evacuation transportation simulation for southeastern Virginia. Study results show how the effects of ATIS can be tested in advance, thus allowing more comprehensive planning by emergency management and transportation professionals. Simulations of ATIS’ effectiveness in evacuation scenarios have been largely unexplored. Methods presented can be applied in a variety of evacuation scenarios and may be of particular value to emergency planners.
Naturalistic Census of Cell Phone Use
Authors: Funkhouser Dillon , Sayer James
Published: January 2013

One hundred eight drivers participated in a naturalistic field operational test. Each participant drove an instrumented passenger car for 6 weeks. Video data from the first week of driving for each participant were visually scored for all instances of cell phone use. These instances were divided into cell phone calls (conversations) and cell phone interactions that were not calls (visual or manual tasks involving the cell phone). Researchers examined 1,382 conversations and 2,149 visual or manual tasks. Participants were engaged in cell phone conversations 6.7% of all driving time and in visual or manual tasks involving a cell phone 2.3% of all driving time. Overall, conversations had a mean duration of 2.6 min, and participants engaged in conversations at a rate of 1.5 conversations per hour. Younger drivers were significantly more likely to be engaged in either type of cell phone task than older drivers and significantly more likely to be engaged in visual or manual tasks than middle-aged drivers. Drivers were more likely to initiate conversations and visual or manual tasks when stopped than at higher speeds; this finding may suggest a level of self-regulation. Furthermore, the finding suggests that estimates of crash risk that are based on assumptions that behavior observed in stopped vehicles translates to behavior in moving vehicles is incorrect and will result in overestimates of driver engagement in cell phone use.
Observational Survey of Cell Phone Use and Texting by California Drivers, 2011
Authors: Cooper Jill F. , Ragland David R. , Ewald Katrin , Wasserman Lisa , Murphy Christopher J.
Published: January 2013

This methodological report describes survey research and data collection methods employed for the first observational survey of cell phone use and texting by California drivers. This study was conducted by Ewald and Wasserman Research Consultants on behalf of the California Office of Traffic Safety and the Safe Transportation Research and Education Center at the University of California, Berkeley. The goal of the survey was to obtain a statewide, statistically representative observational sample. Vehicle drivers were observed at controlled intersections, such as traffic lights and stop signs, using a protocol similar to the National Occupancy Protection Use Study methodology published by the National Highway Traffic Safety Administration. Seventeen California counties were included in the sample frame, and 5,413 valid observations were made. Overall, 4.2% of drivers observed were using a cell phone while driving (phone to ear, manipulating a handheld device, talking on a handheld device, or talking via a headset or Bluetooth device). Because of the difficulty of observing hands-free use, previously used methods were applied to estimate this use at 4.8%. Therefore, an estimate of overall cell phone use in California during the survey period is 9%. California's baseline level of cell phone use and driving will be a critical metric over the years as traffic safety stakeholders mobilize to conduct high-visibility enforcement campaigns, explore new policies, expand educational programs, and engineer countermeasures to increase safety on the roads.
Effect of External Distractions
Authors: Divekar Gautam , Pradhan Anuj Kumar , Pollatsek Alexander , Fisher Donald L.
Published: January 2013

Distractions are a major contributor to automobile crashes, almost one-third of which are thought to be caused by distractions external to the vehicle. Increasingly, external distractions include video billboards, marquees, and variable message signs placed above and beside the highway. It is known that distractions outside the vehicle, especially video billboards, have effects on various vehicle control measures, such as the minimum headway distance to a braking lead vehicle, and that novice drivers and experienced drivers spend equally long times looking at distractions outside the vehicle. In contrast, experienced drivers are much less likely than novice drivers to take long glances at distractions inside the vehicle. This finding raises two questions. First, why are experienced drivers taking such long glances at an external distraction when they are not willing do so when a secondary task arises inside the vehicle? Second, if experienced drivers are sacrificing some of their ability to monitor visible hazards in the roadway ahead, are they sacrificing even more of their ability to anticipate unseen hazards? An experiment to evaluate these two questions had novice and experienced drivers perform an external search task (similar to reading a digital billboard) while driving in a simulator. Monitored throughout were eye movements of the participants and measures of the vehicle, such as lane position and speed. The major finding was that the long glances of both experienced and novice drivers came at the cost of identifying potential hidden hazards and seeing exposed moving threats.
Outbound Texting
Authors: Neurauter M. Lucas , Hankey Jonathan M. , Schalk Thomas B. , Wallace Gary
Published: January 2013

A speech-based system was evaluated to assess general task and on-road performance across vehicular control and subjective measures. The system under evaluation enabled users to send text messages and obtain route guidance through destination entry while driving. A brief introduction to the speech-based system and its capabilities was provided to participants before they were asked to complete three practice tasks. General observations of these initial uninformed interactions (i.e., absent assistance by the experimenter) with the system indicated that the system was intuitive and easy to use. Errors, when observed, were commonly related to word recognition. Participants were then instructed to navigate a closed test track at 72 km/h (45 mph) while engaging in nine secondary tasks: three manual modality texting tasks, three equivalent voice modality texting tasks, and three voice modality destination-entry tasks. As expected, driving performance measures, glance behavior, and subjective ratings were all significantly degraded during manual texting tasks as compared with similar tasks completed using voice commands. Performance during speech-based destination tasks was similar to that observed during speech-based texting. Subjectively, participants generally believed that tasks requiring the use of the speech-based interface could be accomplished safely. The majority of participants (83%) expressed a desire to have this speech-based interface available on their next vehicle.