Aspects of performance of truck weigh stations

1993 ◽  
Vol 20 (3) ◽  
pp. 380-385 ◽  
Author(s):  
Edward S. K. Fekpe ◽  
Alan M. Clayton ◽  
Attahiru Sule Alfa
Keyword(s):  
Service Time ◽  
Arrival Time ◽  
Probability Of Detection ◽  
Erlang Distribution ◽  
Significant Delay ◽  
Truck Traffic ◽  
Queuing Model ◽  
Time Service ◽  
The Impact ◽  
Perceived Probability

The performance characteristics of truck weigh stations are presented. Seasonally operated scales and random inspection sites are found to be at least 3 and 8 times respectively as effective in detecting violations as continuously operated permanent scales with no alternative bypass routes. The availability of alternative bypass routes reduces truckers' perceived probability of detection at permanent weigh scales by at least 5%. Higher perceived probabilities are associated with high inspection rates.Queuing theory is employed to study the impact of two alternative manpower levels on the performance of con tinuously operated permanent weigh scales. For the level of truck traffic volume considered, it is found that, theoretically, there is no significant delay to truck traffic through such weigh scale stations irrespective of the manning strategy. It is concluded that it is feasible to maintain minimal staff at the scales and redirect human resources to increase inspection capacities of other methods.The queuing model for the permanent scale operations represents a rare practical example of a classic M/Ek/1 model where the k stages in the service time Erlang distribution are real and not necessarily imaginary. Key words: permanent scale, effectiveness, enforcement, violation, inspection, arrival time, service time.

scholarly journals Evaluating the impact of new aircraft separation minima on available airspace capacity and arrival time delay

2020 ◽  
Vol 124 (1274) ◽  
pp. 447-471 ◽  
Author(s):  
E. Itoh ◽  
M. Mitici
Keyword(s):  
Delay Time ◽  
Arrival Time ◽  
Flight Time ◽  
Data Driven ◽  
Wake Vortex ◽  
Capacity Control ◽  
Queuing Model ◽  
Air Traffic Controllers ◽  
Arrival Time Delay ◽  
The Impact

AbstractAlthough the application of new, reduced aircraft separation minima can directly increase runway throughput, the impact thereof on the traffic flow of aircraft arriving at the destination airport has not been discussed yet. This paper proposes a data-driven and queue-based modeling approach and presents an analysis of the impact on the delay time of arriving aircraft in the airspace within a radius of 100 nautical miles around an airport. The parameters of our queuing model were estimated by analysing the data contained in the radar tracks and flight plans for flights that arrived at Tokyo International Airport during the 2 years of 2016 and 2017. The results clarified the best arrival strategy according to the distance from the arrival airport: The combination of airspace capacity control and reduction of the flight time and separation variance is the most powerful solution to mitigate delays experienced by arriving traffic while also allowing an increase in the amount of arrival traffic. The application of new wake vortex categories would enable us to increase the arrival traffic to 120%. In addition, the arrival delay time could be minimised by implementing the proposed arrival traffic strategies together with automation support for air traffic controllers.

scholarly journals Measurement of the Sea Surface Height with Airborne GNSS Reflectometry and Delay Bias Calibration

2021 ◽  
Vol 13 (15) ◽  
pp. 3014
Author(s):  
Feng Wang ◽  
Dongkai Yang ◽  
Guodong Zhang ◽  
Jin Xing ◽  
Bo Zhang ◽  
...  
Keyword(s):  
Wind Speed ◽  
Arrival Time ◽  
Elevation Angle ◽  
Satellite System ◽  
Sea Surface Height ◽  
Antenna Pattern ◽  
Sea Surface ◽  
Observation Method ◽  
Global Navigation Satellite ◽  
The Impact

Sea surface height can be measured with the delay between reflected and direct global navigation satellite system (GNSS) signals. The arrival time of a feature point, such as the waveform peak, the peak of the derivative waveform, and the fraction of the peak waveform is not the true arrival time of the specular signal; there is a bias between them. This paper aims to analyze and calibrate the bias to improve the accuracy of sea surface height measured by using the reflected signals of GPS CA, Galileo E1b and BeiDou B1I. First, the influencing factors of the delay bias, including the elevation angle, receiver height, wind speed, pseudorandom noise (PRN) code of GPS CA, Galileo E1b and BeiDou B1I, and the down-looking antenna pattern are explored based on the Z-V model. The results show that (1) with increasing elevation angle, receiver height, and wind speed, the delay bias tends to decrease; (2) the impact of the PRN code is uncoupled from the elevation angle, receiver height, and wind speed, so the delay biases of Galileo E1b and BeiDou B1I can be derived from that of GPS CA by multiplication by the constants 0.32 and 0.54, respectively; and (3) the influence of the down-looking antenna pattern on the delay bias is lower than 1 m, which is less than that of other factors; hence, the effect of the down-looking antenna pattern is ignored in this paper. Second, an analytical model and a neural network are proposed based on the assumption that the influence of all factors on the delay bias are uncoupled and coupled, respectively, to calibrate the delay bias. The results of the simulation and experiment show that compared to the meter-level bias before the calibration, the calibrated bias decreases the decimeter level. Based on the fact that the specular points of several satellites are visible to the down-looking antenna, the multi-observation method is proposed to calibrate the bias for the case of unknown wind speed, and the same calibration results can be obtained when the proper combination of satellites is selected.

Reproductive-cycle plasticity in yellow-cedar (Chamaecyparisnootkatensis)

1991 ◽  
Vol 21 (9) ◽  
pp. 1360-1364 ◽  
Author(s):  
Y. A. El-Kassaby ◽  
J. Maze ◽  
D. A. MacLeod ◽  
S. Banerjee
Keyword(s):  
Reproductive Cycle ◽  
Vancouver Island ◽  
Significant Delay ◽  
Continue Development ◽  
Cold Temperatures ◽  
Size And Shape ◽  
Seed Extraction ◽  
Fresh Pollen ◽  
The Impact

In 1987, a study was initiated to determine the properties of seed from apparently premature cones of yellow-cedar (Chamaecyparisnootkatensis (D. Don) Spach) on southwestern Vancouver Island. After pollination with fresh pollen in February, all cones showed signs of maturation (i.e., drying and shedding) by December. Samples of these 1-year-old cones were collected for seed extraction and germination tests. Germination ranged between 10 and 42% for isolated cones (i.e., bagged) and between 0 and 25% for unisolated cones. Similar germination results were obtained for the 1988 and 1989 cone crops. Anatomical observations revealed that the 10-month-old embryos were similar in both size and shape to embryos from 2-year-old seeds. It was concluded that transplanting yellow-cedar trees to warmer, low-elevation sites enabled seed cones to continue development without significant delay caused by dormancy induced by cold temperatures at higher elevations. This alteration of normal phenology reflects the impact of environmental contingencies on development.

Abstract P99: Impact of the Covid-19 Pandemic on Stroke Thrombolysis Rate and Delay to Thrombolysis Treatment in a Regional Stroke Centre in London, UK

Stroke ◽  
2021 ◽  
Vol 52 (Suppl_1) ◽  
Author(s):  
Brian Drumm ◽  
Paul Bentley ◽  
Zoe Brown ◽  
Lucio D’Anna ◽  
Tsering Dolkar ◽  
...  
Keyword(s):  
Arrival Time ◽  
Negative Impact ◽  
Public Awareness ◽  
Stroke Severity ◽  
Time Intervals ◽  
Neurological Outcomes ◽  
Stroke Thrombolysis ◽  
Prehospital Delays ◽  
The Impact ◽  
Stroke Centre

Introduction: There are reports of changes in the numbers of stroke admissions and time intervals to receiving emergency treatments during the COVID-19 pandemic. We examined the impact of the COVID-19 pandemic on the stroke thrombolysis rate and delay to thrombolysis treatment in a regional stroke centre in London, UK. Methods: COVID-19 testing began at our hospital on 3 March 2020. Clinical data for all acute stroke admissions were routinely collected as part of a national Sentinel Stroke National Audit Programme (SSNAP) and all thrombolysis data were entered into our local thrombolysis database. We retrospectively extracted the relevant patient data for the period of March to May 2020 (COVID group) and compared to the same period in 2019 (pre-COVID group). Results: Compared with pre-COVID, there was a 17.5% fall in total stroke admissions (from 315 to 260) during COVID; but there were no significant differences in the demographics, stroke severity, proportions with known time of onset, or median onset-to-arrival time. The thrombolysis rates amongst ischemic strokes were not significantly different between the two groups (59/260=23% pre-COVID vs. 41/228=18% COVID, p=.19). For thrombolysis patients, their stroke severity and demographics were similar between the two both groups. Median onset-to-needle time was significantly longer by 22 minutes during COVID [127 (IQR 94-160) vs. 149 (IQR 110-124) minutes, p=.045]; this delay to treatment was almost entirely due to a longer median onset-to-arrival time by 16 minutes during COVID (p=.029). Favorable early neurological outcomes post-thrombolysis (defined as an improvement in NIHSS by ≥4 points at 24 hours) were similar (45% vs. 46%, p=.86). Conclusion: COVID-19 pandemic had a negative impact on prehospital delays which in turn significantly increased onset-to-needle time, but without affecting the chance of a favorable early neurological outcome. Our data highlight the need to maintain public awareness of taking immediate action when stroke symptoms occur during the COVID-19 pandemic.

Modeling Bus Capacity for Bus Stops Using Queuing Theory and Diffusion Approximation

2021 ◽  
pp. 036119812110302
Author(s):  
Chao Wang ◽  
Weijie Chen ◽  
Yueru Xu ◽  
Zhirui Ye
Keyword(s):  
Approximation Method ◽  
Service Time ◽  
Diffusion Approximation ◽  
Coefficient Of Variation ◽  
Queuing Theory ◽  
Queuing Model ◽  
Bus Stop ◽  
Proposed Model ◽  
Bus Stops ◽  
Bus Service

For bus service quality and line capacity, one critical influencing factor is bus stop capacity. This paper proposes a bus capacity estimation method incorporating diffusion approximation and queuing theory for individual bus stops. A concurrent queuing system between public transportation vehicles and passengers can be used to describe the scenario of a bus stop. For most of the queuing systems, the explicit distributions of basic characteristics (e.g., waiting time, queue length, and busy period) are difficult to obtain. Therefore, the diffusion approximation method was introduced to deal with this theoretical gap in this study. In this method, a continuous diffusion process was applied to estimate the discrete queuing process. The proposed model was validated using relevant data from seven bus stops. As a comparison, two common methods— Highway Capacity Manual (HCM) formula and M/M/S queuing model (i.e., Poisson arrivals, exponential distribution for bus service time, and S number of berths)—were used to estimate the capacity of the bus stop. The mean absolute percentage error (MAPE) of the diffusion approximation method is 7.12%, while the MAPEs of the HCM method and M/M/S queuing model are 16.53% and 10.23%, respectively. Therefore, the proposed model is more accurate and reliable than the others. In addition, the influences of traffic intensity, bus arrival rate, coefficient of variation of bus arrival headway, service time, coefficient of variation of service time, and the number of bus berths on the capacity of bus stops are explored by sensitivity analyses.

scholarly journals Impact of the assimilation of lightning data on the precipitation forecast at different forecast ranges

2017 ◽  
Vol 14 ◽  
pp. 187-194 ◽  
Author(s):  
Stefano Federico ◽  
Marco Petracca ◽  
Giulia Panegrossi ◽  
Claudio Transerici ◽  
Stefano Dietrich
Keyword(s):  
Data Assimilation ◽  
Mesoscale Model ◽  
Weather Prediction ◽  
Horizontal Resolution ◽  
Probability Of Detection ◽  
Precipitation Forecast ◽  
Time Range ◽  
False Alarms ◽  
Forecast Time ◽  
The Impact

Abstract. This study investigates the impact of the assimilation of total lightning data on the precipitation forecast of a numerical weather prediction (NWP) model. The impact of the lightning data assimilation, which uses water vapour substitution, is investigated at different forecast time ranges, namely 3, 6, 12, and 24 h, to determine how long and to what extent the assimilation affects the precipitation forecast of long lasting rainfall events (> 24 h). The methodology developed in a previous study is slightly modified here, and is applied to twenty case studies occurred over Italy by a mesoscale model run at convection-permitting horizontal resolution (4 km). The performance is quantified by dichotomous statistical scores computed using a dense raingauge network over Italy. Results show the important impact of the lightning assimilation on the precipitation forecast, especially for the 3 and 6 h forecast. The probability of detection (POD), for example, increases by 10 % for the 3 h forecast using the assimilation of lightning data compared to the simulation without lightning assimilation for all precipitation thresholds considered. The Equitable Threat Score (ETS) is also improved by the lightning assimilation, especially for thresholds below 40 mm day−1. Results show that the forecast time range is very important because the performance decreases steadily and substantially with the forecast time. The POD, for example, is improved by 1–2 % for the 24 h forecast using lightning data assimilation compared to 10 % of the 3 h forecast. The impact of the false alarms on the model performance is also evidenced by this study.

scholarly journals APLIKASI PENGINDERAAN JAUH DAN SISTEM INFORMASI GEOGRAFI UNTUK PEMETAAN DAERAH BERPOTENSI TSUNAMI DI KABUPATEN KUPANG PROVINSI NUSA TENGGARA TIMUR

2018 ◽  
Vol 3 (2) ◽  
pp. 170-178
Author(s):  
Lidia Agustina Rumaal ◽  
Jehunias L. Tanesib ◽  
Jonshon Tarigan
Keyword(s):  
Remote Sensing ◽  
Information System ◽  
Geographic Information System ◽  
Population Density ◽  
Land Cover ◽  
Arrival Time ◽  
Land Cover Map ◽  
The Impact ◽  
Monitoring Area ◽  
Wave Arrival

Abstrak Telah dilakukan pemetaan daerah rawan tsunami berdasarkan estimasi waktu tiba gelombang dan tutupan lahan di Kabupaten Kupang Provinsi Nusa Tenggara Timur menggunakan aplikasi Penginderaan Jauh dan Sistem Informasi Geografi. Penelitian ini bertujuan untuk mengidentifikasi, memetakan daerah rawan tsunami dan tingkat kerawanannya menurut estimasi waktu tiba gelombang dan tutupan lahan sebagai upaya mitigasi dampak bencana tsunami terhadap kepadatan penduduk. Metode penelitian secara umum dibagi dalam empat tahap utama yaitu pembangunan basis data berupa pembuatan peta tutupan lahan, peta gempa dan peta batimetri. Analisis data kerawanan dari peta tutupan lahan dan etimasi waktu tiba gelombang, penyajian hasil data dalam bentuk tingkat kerawanan masing-masing peta dan analisis hasil penelitian berupa tingkat kerawanan secara kualitatif masing-masing daerah titik pantau menurut peta tutupan lahan maupun estimasi waktu tiba gelombang. Selain itu, dampak kerawanan tsunami diklasifikasikan menurut tingkat kepadatan penduduk untuk kebutuhan mitigasi sebagai berikut Kecamatan Kupang Timur, Kupang Barat, Sulamu, Amfoang Timur, Semau, Semau Selatan, Amfoang Utara, Amfoang Barat Daya, Amfoang Barat Laut dan Fatuleu Barat. Kata kunci : Peta rawan tsunami, Penginderaan Jauh, Sistem Informasi Geografi, Estimasi Waktu Tiba Gelombang  Abstract Mapping of hazard tsunami areas based on estimation of arrival time of wave and land cover in Kupang Regency of East Nusa Tenggara Province using remote sensing application and geographic information system has been done. The  aims of this research are to mapping the hazard tsunami area and tsunami vulnerability level in Kupang Regency East Nusa Tenggara according to the estimated arrival time of the wave and land cover as an effort to mitigate the impact of the tsunami disaster on population density. These generally devided into four main phase namely development of database in the form of land cover map , seismic maps and bathymetry maps, data analysis of research results in the form of qualitative vulnerability of each monitoring area according to land cover map and estimated wave arrival time. Presentation of data results in the form of vulnerability level of each map and analysis and results analysis of research the form of vulnerability level of each map and analysis of research results in the form of qualitative vulnerability of each monitoring area according to land cover map and estimated wave arrival time. And then, the impact of tsunami vulnerability is classified according to population density levels for mitigation needs as follows Kupang Timur, Kupang Barat, Sulamu, Amfoang Timur, Semau, Semau Selatan, Amfoang Utara, Amfoang Barat Daya, Amfoang Barat Laut and Fatuleu Barat. Keywords: Tsunami Hazard Map, Remote Sensing, Geographic Information System, Estimated Time of arrival Wave

scholarly journals Analysis of queue change of visitors and performace system in the Department of Population and Civil Regristation of Semarang City

2020 ◽  
Vol 202 ◽  
pp. 15005
Author(s):  
Sugito ◽  
Alan Prahutama ◽  
Dwi Ispriyanti ◽  
Mustafid
Keyword(s):  
Customer Satisfaction ◽  
Waiting Time ◽  
Public Service ◽  
Service Time ◽  
Service Sector ◽  
General Distribution ◽  
Queuing Systems ◽  
Queuing Model ◽  
The Public ◽  
Second Period

The Population and Civil Registry Office in Semarang city is one of the public service units. In the public service sector, visitor / customer satisfaction is very important. It can be identified by the length of the queue, the longer visitors queue this results in visitor dissatisfaction with the service. Queue analysis is one of the methods in statistics to determine the distribution of queuing systems that occur within a system. In this study, a queuing analysis as divided into two periods. The first period lasts from 2-13 March 2015, while the second period lasts November 16th to December 20th 2019. The variables used are the number of visitors and the service time at each counter in intervals of 30 minutes. The results obtained are changes in the distribution and queuing model that is at counter 5/6 and counter 10. The queuing model obtained at the second perideo for the number of visitors and the time of service with a General distribution. The average number of visitors who come in 30 minute intervals in the second period is more than the first period, this indicates an increase in visitors. The opportunity for service units is still small, the waiting time in the queue is getting smaller. This shows that the performance of the queuing system at the Semarang Population and Civil Registry Office is getting better.

Abstract P153: SARS-CoV-2 (COVID-19) Protection Efforts on Acute Stroke Treatment

Stroke ◽  
2021 ◽  
Vol 52 (Suppl_1) ◽  
Author(s):  
Jessica Greenwood ◽  
Starlie Belnap ◽  
Rodney Bedgio ◽  
Guilherme Dabus ◽  
Italo Linfante ◽  
...  
Keyword(s):  
Stroke Volume ◽  
Endovascular Treatment ◽  
Acute Stroke ◽  
Symptom Onset ◽  
Onset Time ◽  
Fold Increase ◽  
Medical Attention ◽  
Hospital Treatment ◽  
Significant Delay ◽  
The Impact

Introduction: It is unclear how the interventions designed to restrict community and in-hospital exposure to the SARS-CoV-2 virus affected the care for stroke patients seeking acute treatment. The objective of the following study was to determine the impact COVID-19 has had on the treatment times for patients evaluated as acute stroke alerts at Baptist Hospital of Miami (BHM). A co-primary objective of the study was to assess the risk of contracting SARS-CoV-2 within 2 weeks from hospital discharge. Methods: This retrospective, two phase study was conducted between December 2019 and April 2020. In phase one, we assessed time from symptom onset to hospital arrival, number of strokes with witnessed onset, and in-hospital treatment times pre & post implementation of Covid-19 preventive exposure measures. In phase two of the study, a telephone survey was conducted on the post implementation group to assess the risk of patients developing symptoms or testing positive for SARS-CoV-2 from hospital admission up to two weeks post discharge. Results: Phase I demonstrated there was a 40% decline in stroke volume, but no significant delay to seek medical attention post implementation of the SARS prevention strategies. On average individuals in the pre-group (n=155) waited approximately 260 minutes (SE=24) to seek medical attention vs. 203 minutes (SE=27) minutes for the post-group (n=87). However, there was nearly a six-fold increase in the percentage of cases with unknown symptom onset post implementation of COVID-19 safety precautions. There was significant delay in administering IV alteplase, increasing from 24 mins (n=16) to 33 mins (n=21) post implementation; delays observed for endovascular treatment were not significant (pre, n=13 mean= 73 mins, post n=12 mean= 82 mins). The volume of patients treated with either IV alteplase and/or endovascular treatment remained similar. Phase II of the study is on-going, results will be available for the ISC. Discussion: The COVID-19 crisis in our community was associated with a six-fold increase in the percentage of cases with unknown stroke onset time. Besides a marked decrease in stroke volume, we did not evidence significant delays to either seek or provide acute stroke care outside a modest increase in door to needle time.

scholarly journals Considering different recent advancements in GNSS on real-time zenith troposphere estimates

GPS Solutions ◽  
2020 ◽  
Vol 24 (4) ◽  
Author(s):  
Tomasz Hadas ◽  
Thomas Hobiger ◽  
Pawel Hordyniec
Keyword(s):  
Real Time ◽  
Weighting Function ◽  
Functional Model ◽  
Processing Parameters ◽  
Gradient Estimation ◽  
International Gnss Service ◽  
Total Delay ◽  
Time Service ◽  
Gnss Meteorology ◽  
The Impact

Abstract Global navigation satellite system (GNSS) remote sensing of the troposphere, called GNSS meteorology, is already a well-established tool in post-processing applications. Real-time GNSS meteorology has been possible since 2013, when the International GNSS Service (IGS) established its real-time service. The reported accuracy of the real-time zenith total delay (ZTD) has not improved significantly over time and usually remains at the level of 5–18 mm, depending on the station and test period studied. Millimeter-level improvements are noticed due to GPS ambiguity resolution, gradient estimation, or multi-GNSS processing. However, neither are these achievements combined in a single processing strategy, nor is the impact of other processing parameters on ZTD accuracy analyzed. Therefore, we discuss these shortcomings in detail and present a comprehensive analysis of the sensitivity of real-time ZTD on processing parameters. First, we identify a so-called common strategy, which combines processing parameters that are identified to be the most popular among published papers on the topic. We question the popular elevation-dependent weighting function and introduce an alternative one. We investigate the impact of selected processing parameters, i.e., PPP functional model, GNSS selection and combination, inter-system weighting, elevation-dependent weighting function, and gradient estimation. We define an advanced strategy dedicated to real-time GNSS meteorology, which is superior to the common one. The a posteriori error of estimated ZTD is reduced by 41%. The accuracy of ZTD estimates with the proposed strategy is improved by 17% with respect to the IGS final products and varies over stations from 5.4 to 10.1 mm. Finally, we confirm the latitude dependency of ZTD accuracy, but also detect its seasonality.

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