Arrival Delay Research Articles

Quantitative characterization of interface delamination in composite T-joint using couplant-free Lamb wave methods

Research in quick Non-Destructive Evaluation methods for field maintenance of aircraft has become a focus of attention due to increase in the use of co-cured skin-stiffened composite structures. When Lamb wave propagates over skin-stiffened structure, the occurrence of multiple modes is unavoidable due to structural features such as stringers and stiffeners, which in turn makes the interpretation of the received wave difficult and limits the defect-detection ability of Lamb waves. Using Finite Element simulations, the propagation of incident S0 Lamb mode in a typical composite T-joint with delamination between the flange and skin (interface) is investigated. Arrival time delays of the out-of-plane mode-converted wave packets are found to be promising indicator for quantitative detection and sizing of the delamination. A novel experimental technique of combining a liquid couplant-free transduction scheme using dry-coupled roller transducer (contact probe) for generating S0 mode and an air-coupled transducer (non-contact probe) as a receiver is proposed. This transduction scheme helps in selectively separating mode-converted wave packets. This investigation also establishes quantitative B-scan imaging method for characterization of delamination in the T-joint. Experimental results show a good agreement with Finite Element predictions.

The delay in arrival of the parasitoid Diaeretiella rapae influences the efficiency of cabbage aphid biological control

The efficiency of the biological control strategies based on parasitoids, either as a release or a conservative measure, depends on the timely arrival or release of the parasitoids after colonization of the field by the pest. In this study, the effects of the delay between the cabbage aphid Brevicoryne brassicae (Hemiptera: Aphididae) infestation and the release of its parasitoid Diaeretiella rapae (Hymenoptera: Braconidae) and of the number of parasitoid releases on aphid population dynamics and host plant growth were investigated. When the parasitoids were released at the start of the infestation, 89.6 % of the aphids were parasitized one month later, and the damage to cabbage was low. The identical number of parasitoids released two weeks after the start of the infestation partially controlled the aphid population, but the growth of the cabbage was altered. The earliest introduction of the parasitoid to the crop led to an efficient host regulation, and the release in three times rather than in one time did not improve the control efficiency at this release delay. The implications for biological control strategies that use parasitoids of aphids are discussed.

ON THE COMPLEX VARIABILITY OF THE SUPERORBITAL MODULATION PERIOD OF LMC X-4

LMC X-4 is an eclipsing high-mass X-ray binary exhibiting a superorbital modulation with a period of ~ 30:5 days. We present a detailed study of the variations of the superorbital modulation period with a time baseline of ~ 18 years. The period determined in the light curve collected by the Monitor of All-sky X-ray Image (MAXI) significantly deviates from that observed by the All Sky Monitor (ASM) onboard the Rossi X-ray Timing Explorer (RXTE). Using the data collected by RXTE/ASM, MAXI, and the Burst Alert Telescope (BAT) onboard Swift, we found a significant period derivative, <TEX>$\dot{P}=(2.08{\pm}0.12){\times}10^{-5}$</TEX>. Furthermore, the O{C residual shows complex short-term variations indicating that the superorbital modulation of LMC X-4 exhibits complicated unstable behaviors. In addition, we used archive data collected by the Proportional Counter Array (PCA) on RXTE to estimate the orbital and spin parameters. The detected pulse frequencies obtained in small time segments were fitted with a circular orbital Doppler shift model. In addition to orbital parameters and spin frequency for each observation, we found a spin frequency derivative of <TEX>$\dot{v}=(6.482{\pm}0.011){\times}10^{-13}Hz{\cdot}s^{-1}$</TEX>. More precise orbital and spin parameters will be evaluated by the pulse arrival time delay technique in the future.

Coherent, very high frequency underwater acoustic communications under wind-driven seas: Experiments in an ocean simulator

Very high frequency, underwater water acoustic communications (VHF UWAC) operated near the sea surface are subject to interference from surface-scattered energy and, under wind driven seas, noise from breaking waves. Here, we present results from experiments to study these effects conducted in an ocean simulator. Acoustic transmissions in the frequency range (400–750) kHz were made using vertical arrays of transducers in the 44 m long, 2.4 m wide, and 1.5 m deep wind-wave channel at the Hydraulics Laboratory at Scripps Institution of Oceanography. This facility simulates oceanic conditions with a piston wave maker and a fan driving airflows up to 15 m/s. A variety of communications and probe signals were sent under calm and wind-driven conditions. Surface scattering was characterized in terms of arrival delay and gravity wave focusing, along with measurements of breaking wave noise. These data will be discussed in terms of VHF UWAC performance.

철도선로용량 부족에 따른 지체발생 연구 - 경부선 서울~금천구청 구간을 대상으로

This research shows the relationship between the number of trains and the probability of trains with arrival delay and suggests way to estimate the benefits of improved punctuality in a bottleneck section of the Gyeongbu Line. The arrival delays of high-speed and conventional trains were estimated using the train operation data of KORAIL. Linear regression models for the probability of trains with arrival delay by train type are presented in this paper. The probabilities of trains with arrival delay were more affected by the number of conventional trains than by the number of high-speed rail trains. For the empirical analysis, a project for increasing the capacity in the Seoul~Geumcheongu office section was tested. The benefits of the improved punctuality were estimated to be 4.2~4.5 billion Korean won every year. This research has some limitations but it can help evaluate more precisely the feasibility of the project of increasing the capacity in bottleneck sections.

How far is arterial spin labeling MRI from a clinical reality? Insights from arterial spin labeling comparative studies in Alzheimer's disease and other neurological disorders.

How far is arterial spin labeling MRI from a clinical reality? Insights from arterial spin labeling comparative studies in Alzheimer's disease and other neurological disorders.

Acute stroke: why do some patients arrive in time and others do not?

The aim of this study was to evaluate which factors are associated with early hospital arrival and help-seeking delays in acute stroke. All consecutive eligible patients were interviewed face-to-face within 72 h of admission. Factors associated with early arrival were assessed by univariate and multivariate analysis. The data of 195 patients were analysed. The patients who first called the emergency medical services rather than the family physician arrived earlier (odds ratio 15.9, 95% confidence interval 3.23-78.3, P<0.01). Those who contacted the emergency medical services within 30 min of symptom onset were more likely to receive thrombolysis (odds ratio 6.9, 95% confidence interval 2.6-18.4, P<0.01). The most common reasons for delaying seeking help were the hope for spontaneous recovery and perceiving the elapsed time as insignificant. The patients who call their family physician lose valuable time and their chance for thrombolysis. Many patients probably neglect symptoms because of stroke itself and therefore do not act fast enough.

English

AIM: To study the clinical profile and visual outcome in children with traumatic endophthalmitis undergoing vitrectomy. METHODS: A retrospective analysis was performed from hospital records of Minto ophthalmic hospital, Bangalore between 1 st April 2014 to 31 st March 2015 on traumatic endophthalmitis in children less than 15 yrs. Complete ocular examination along with B scan was done and endophthalmitis was confirmed. Systemic evaluation and necessary blood investigations for general anaesthesia were done.23 Gauge Three port pars plana Vitrectomy was done as early as possible. RESULTS: A total of ten children with traumatic endophthalmitis who underwent vitrectomy for traumatic endopthalmitis between July 2014 to April 2015 were studied. Nine cases presented with corneal tear and one case presented with self- sealed scleral tear. Nine cases underwent primary tear repair with intravitreal antibiotics, followed by an early vitrectomy and one case underwent primary tear repair and vitrectomy as a single procedure. Vitreous biopsy was sent for grams stain, KOH mount and culture and sensitivity. Nine cases underwent lensectomy along with vitrectomy. One case underwent repeat vitrectomy after 4 day since the exudates filled the vitreous cavity. Two cases developed retinal detachment and underwent surgery for the same. At the end of two months 3 cases had vision of 6/24 or better, three cases had vision of 1/60 and 4 cases had total retinal detachment with subsequent phthisis bulbi. CONCLUSION: Nature of injury, delay in communication by the children, delay in observation by the parents, delay in arrival for treatment and virulence of the organism may result in poor visual prognosis in children with endophthalmitis.

Linking business strategy to service failures and financial performance: Empirical evidence from the U.S. domestic airline industry

Developing an understanding of the relationship between service quality and profitability is of central importance to operations management scholars. In this study we seek to reconcile inconsistencies between extant theory and empirical findings regarding the relationship between service quality and profitability in the airline industry. More specifically, we draw on theories from strategic management, operations strategy, and economics to explain why the relationship between measures of service quality and profitability will be moderated by an airline's competitive strategy. We test our hypotheses by fitting mixed-effects models to longitudinal data obtained from several governmental databases in the context of the U.S. domestic airline industry. We find that airline strategy moderates the relationship between some service failures and profitability. Specifically, we find that mishandled baggage and customer complaints more negatively affect the profitability of focused than non-focused airlines. We also find the relationship between arrival delays on profitability is universally negative for focused airlines, but displays an inverted U-shaped relationship for non-focused airlines. Our findings provide significant contributions to the existing body of knowledge in service quality and operations strategy. We further outline the implications of these findings for practice and future research.

Approximate path searching for supporting shortest path queries on road networks

Although various efficient indexing techniques have been proposed to improve the performance in distributing road data to mobile clients to perform shortest path searches on road networks, how to minimize the tune-in and path searching costs are still important performance goals since the clients usually have limited processing capability and energy supply. In this paper, based on the Next Region (NR) approach, we propose a new method called Approximate Path Searching (APS) for constructing the broadcast index at mobile clients with soft arrival times to destinations. APS adopts an approximation technique in calculating the sets of required regions for each <start, destination> region pair in a road network to reduce the index generation cost at the road server and the tune-in and path searching costs at the clients. Different from NR, which only provides one set of required regions containing the shortest path from a client’s start region to its destination region, APS generates n-sets of required regions for a client to choose. Each set of required regions contains different numbers of regions. Although choosing a smaller region set may give a slightly longer delay in arrival, the tune-in and path searching costs could be significantly reduced. Theoretical analysis and extensive simulation experiments have been performed to demonstrate the effectiveness of APS in improving the system performance with just a few percentages delay in arrival time on average comparing with NR using data sets from real road networks.

Tyranny of distance and rural prehospital care: Is there potential for a national rural responder network?

Critical illness intersects with the workload of rural doctors in Australia, mostly via their on-call responsibilities to rural hospitals. A significant proportion of these are prehospital incidents - vehicle crashes, farming injuries, bushfire etc. Effective care for such patients requires an integration of prehospital ambulance services, retrieval services and tertiary level trauma services all the way through to rehabilitation. Ambulance services in rural areas are often volunteer based, and with increasing remoteness via the 'tyranny of distance' comes the likelihood of increased delay in arrival of specialist retrieval services. Potential exists to utilise rural clinicians to respond to prehospital incidents in certain defined circumstances, as suggested by a recent survey of rural doctors.

Passive Acoustic Source Localization at a Low Sampling Rate Based on a Five-Element Cross Microphone Array.

Accurate acoustic source localization at a low sampling rate (less than 10 kHz) is still a challenging problem for small portable systems, especially for a multitasking micro-embedded system. A modification of the generalized cross-correlation (GCC) method with the up-sampling (US) theory is proposed and defined as the US-GCC method, which can improve the accuracy of the time delay of arrival (TDOA) and source location at a low sampling rate. In this work, through the US operation, an input signal with a certain sampling rate can be converted into another signal with a higher frequency. Furthermore, the optimal interpolation factor for the US operation is derived according to localization computation time and the standard deviation (SD) of target location estimations. On the one hand, simulation results show that absolute errors of the source locations based on the US-GCC method with an interpolation factor of 15 are approximately from 1/15- to 1/12-times those based on the GCC method, when the initial same sampling rates of both methods are 8 kHz. On the other hand, a simple and small portable passive acoustic source localization platform composed of a five-element cross microphone array has been designed and set up in this paper. The experiments on the established platform, which accurately locates a three-dimensional (3D) near-field target at a low sampling rate demonstrate that the proposed method is workable.

Analysis of Lost Sonographer Productivity in a University Hospital Vascular Laboratory

Introduction Improved efficiency is necessary to deliver cost effective services in today's healthcare environment. Details of how a vascular sonographer's (SG) time is allocated during an average working day have not been adequately described previously. Our objective was to provide insight into the SG average day, and therefore investigate ways at becoming more efficient. This improved efficiency may not only result in cost savings, but better patient and SG satisfaction. Methods SG at two hospitals affiliated with our university (Hospital A and B) tracked their activities daily during five consecutive weekdays. Scan time, delays in patient arrival, preparation for the test, computer entry, lunch breaks, and administrative time (patient and nonpatient related) were logged. Results Eleven SG performed 113 tests at Hospital A and 60 at Hospital B. On average, there were 5.4 full time equivalent (FTE) and 1.8 FTE SG working daily at Hospitals A and B respectively. Hospital A performed 62 portable studies, Hospital B performed none. Each SG performed between 14 and 32 tests (mean 21.4) in the study period. This was equivalent to 6.35 tests per FTE per day. Excluding portable studies, actual scan time occupied only 38.8% of the SG day. Nonpatient related but essential activities (23.7%) and nonscan nonessential activities (27.9%) took up the rest of the SG time. Conclusion In order to maximize efficiency in the vascular lab, nonpatient related activities, which occupy about a quarter of the daily workday, must be eliminated. Off-loading of these responsibilities to ancillary staff may improve SG efficiency. Portable studies consume a significant amount of time, and thus are a drag on efficiency as well.

Deriving the orbital properties of pulsators in binary systems through their light arrival time delays

We present the latest developments to the phase modulation method for finding binaries among pulsating stars. We demonstrate how the orbital elements of a pulsating binary star can be obtained analytically, that is, without converting time delays to radial velocities by numerical differentiation. Using the time delays directly offers greater precision, and allows the parameters of much smaller orbits to be derived. The method is applied to KIC9651065, KIC10990452, and KIC8264492, and a set of the orbital parameters is obtained for each system. Radial velocity curves for these stars are deduced from the orbital elements thus obtained.

Analyzing passenger train arrival delays with support vector regression

We propose machine learning models that capture the relation between passenger train arrival delays and various characteristics of a railway system. Such models can be used at the tactical level to evaluate effects of various changes in a railway system on train delays. We present the first application of support vector regression in the analysis of train delays and compare its performance with the artificial neural networks which have been commonly used for such problems. Statistical comparison of the two models indicates that the support vector regression outperforms the artificial neural networks. Data for this analysis are collected from Serbian Railways and include expert opinions about the influence of infrastructure along different routes on train arrival delays.

Normalization and source separation of acoustic emission signals for condition monitoring and fault detection of multi-cylinder diesel engines

A signal processing technique is presented in this paper to normalize and separate the source of non-linear acoustic emission (AE) signals of a multi-cylinder diesel engine for condition monitoring applications and fault detection. The normalization technique presented in the paper overcomes the long-existing non-linearity problem of AE sensors so that responses measured by different AE sensors can be quantitatively analysed and compared. A source separation algorithm is also developed in the paper to separate the mixture of the normalized AE signals produced by a multi-cylinder diesel engine by utilising the system parameters (i.e., wave attenuation constant and the arrival time delay) of AE wave propagation determined by a standard pencil lead break test on the engine cylinder head. It is shown that the source separation algorithm is able to separate the signal interference of adjacent cylinders from the monitored cylinder once the wave attenuation constant and the arrival time delay along the propagation path are known. The algorithm is particularly useful in the application of AE technique for condition monitoring of small-size diesel engines where signal interference from the neighbouring cylinders is strong.

EVALUATION OF FACTOR AFFECTING FOR LABOUR PRODUCTIVITY IN CONSTRUCTION PROJECT BY AHP

The study aims at identifying the factors an affecting labor productivity of Building construction projects in the South Gujarat. . To do so, as per sample size 350 Stakeholders working in construction completed a structured questionnaire survey ranked the identified factors according to analytical hierarchy process. 40 factors were identified through a detailed literature review. Factors of similar nature were grouped together; giving rise to seven main groups that are: technical, labor, materials, equipments, external &amp;environmental, safety and quality. The analysis of the identified factors indicated that the top ten important factors negatively aecting labor productivity of building construction projects in South Gujarat are: quality inspection delay, working at high places, rework, low quality raw material, lack of material, delay in arrival of material, equipment shortage, lack of labour skill, payment delay

Delay-sensitive and delay-insensitive deconvolution perfusion-CT: similar ischemic core and penumbra volumes if appropriate threshold selected for each.

Perfusion-CT (PCT) processing involves deconvolution, a mathematical operation that computes the perfusion parameters from the PCT time density curves and an arterial curve. Delay-sensitive deconvolution does not correct for arrival delay of contrast, whereas delay-insensitive deconvolution does. The goal of this study was to compare delay-sensitive and delay-insensitive deconvolution PCT in terms of delineation of the ischemic core and penumbra. We retrospectively identified 100 patients with acute ischemic stroke who underwent admission PCT and CT angiography (CTA), a follow-up vascular study to determine recanalization status, and a follow-up noncontrast head CT (NCT) or MRI to calculate final infarct volume. PCT datasets were processed twice, once using delay-sensitive deconvolution and once using delay-insensitive deconvolution. Regions of interest (ROIs) were drawn, and cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) in these ROIs were recorded and compared. Volume and geographic distribution of ischemic core and penumbra using both deconvolution methods were also recorded and compared. MTT and CBF values are affected by the deconvolution method used (p < 0.05), while CBV values remain unchanged. Optimal thresholds to delineate ischemic core and penumbra are different for delay-sensitive (145 % MTT, CBV 2 ml × 100 g(-1) × min(-1)) and delay-insensitive deconvolution (135 % MTT, CBV 2 ml × 100 g(-1) × min(-1) for delay-insensitive deconvolution). When applying these different thresholds, however, the predicted ischemic core (p = 0.366) and penumbra (p = 0.405) were similar with both methods. Both delay-sensitive and delay-insensitive deconvolution methods are appropriate for PCT processing in acute ischemic stroke patients. The predicted ischemic core and penumbra are similar with both methods when using different sets of thresholds, specific for each deconvolution method.

센서네트워크 내에서 TDOA 측정치 기반의 이동 표적 속도 정보 추정

In the moving target problem, the velocity information of the moving target is very important as well as the high accuracy position information. To solve this problem, active researches are being conducted recently with combine the Time Difference of Arrival (TDOA) and Frequency Delay of Arrival(FDOA) measurements. However, since the FDOA measurement is utilizing the Doppler effect due to the relative velocity between the target source and the receiver sensor, it may be difficult to use the FDOA measurement if the moving target speed is not sufficiently fast. In this paper, we propose a method for estimating the position and the velocities of the target by using only the TDOA measurements for the low speed moving target in the indoor environment with sensor network. First, the target position and heading angle are obtained from the estimated positions of two attached transmitters on the target. Then, the target angular and linear velocities are also estimated. In addtion, we apply the Instrumental Variable (IV) technique to compensate the estimation error of the estimated target velocity. In simulation, the performance of the proposed algorithm is verified.

Abstract T P399: Patient Characteristics and Outcomes in Pregnancy-Related Subarachnoid Hemorrhage

Background: Subarachnoid hemorrhage (SAH) accounts for up to 4.1% of all pregnancy-related in-hospital deaths, but is less often aneurysmal and is associated with better short term outcomes than in non-pregnant patients. We sought to describe the risk factors, management and outcomes of pregnant vs. non-pregnant patients with SAH in the Get With The Guidelines (GWTG) Stroke Registry. Methods: Using medical history or ICD-9 codes, we identified 152 pregnant and 5745 non-pregnant SAH female patients aged 18-44 with SAH in GWTG from 2008-2013. Differences in characteristics were compared by Chi-square tests for categorical and Wilcoxon Rank-Sum tests for continuous variables. Stratified logistic regression assessed the effect of pregnancy on outcomes conditional on age and adjusted for patient and hospital characteristics. Results: Pregnant SAH patients were younger, more often black and insured with Medicaid. They had higher initial blood pressure (BP) and were less likely to report prior hypertension. Arrival delays from stroke onset were common in both groups (median 340 vs. 277 min), but pregnant SAH patients were more often already hospitalized at stroke onset (16% vs. 10%). Fewer pregnant vs. non-pregnant SAH patients had initial neurologic exam findings recorded (Table). Pregnant SAH patients had lower in-hospital death than non-pregnant patients (aOR 0.17, 95% CI 0.06-0.45) and were more likely at discharge to ambulate independently (aOR 2.40, 95% CI 1.56-3.69) and return home (aOR 2.60, 95% CI 1.67-4.06). Conclusions: Several differences exist between pregnant and non-pregnant women with SAH. Many present with BP well below the threshold for hypertensive disorders of pregnancy, making prompt recognition and prevention of brain hemorrhage challenging. Overall, pregnancy-related SAH is associated with less morbidity and mortality than non-pregnancy related disease.