Acceptable Time Delay Research Articles

The study of frictional damper with various control algorithms

Frictional dampers are used in structural engineering as means of passive control. Meanwhile, frictional damper shave a disadvantage compared to viscous rivals since the slippage force must be exceeded to activate the device, and cannot be ideal full range of possible events. The concept of semi-active control is utilized to overcome this shortcoming. In this paper, a new semi-active frictional damper called Smart Adjustable Frictional (SAF) damper is introduced. SAF damper consists of hydraulic, electronic units and sensors which are all linked with an active control discipline. SAF acts as a smart damper which can adapt its slippage threshold during a dynamic excitation by measuring and controlling the structural response. The novelty of this damper is, while it controls the response of the structure in real time with acceptable time delay. The paper also reports on the results of a series of experiments which have been performed on SAF dampers to obtain their prescribed hysteretic behavior for various control algorithms. The results show that SAF can produce the desired slippage load of various algorithms in real time. Numerical models incorporating control simulations are also made to obtain the hysteretic response of the system which agrees closely with test results.

Multi-objective optimization of MOSFETs channel widths and supply voltage in the proposed dual edge-triggered static D flip-flop with minimum average power and delay by using fuzzy non-dominated sorting genetic algorithm-II

BackgroundD Flip-Flop as a digital circuit can be used as a timing element in many sophisticated circuits. Therefore the optimum performance with the lowest power consumption and acceptable delay time will be critical issue in electronics circuits.FindingsThe newly proposed Dual-Edge Triggered Static D Flip-Flop circuit layout is defined as a multi-objective optimization problem. For this, an optimum fuzzy inference system with fuzzy rules is proposed to enhance the performance and convergence of non-dominated sorting Genetic Algorithm-II by adaptive control of the exploration and exploitation parameters. By using proposed Fuzzy NSGA-II algorithm, the more optimum values for MOSFET channel widths and power supply are discovered in search space than ordinary NSGA types. What is more, the design parameters involving NMOS and PMOS channel widths and power supply voltage and the performance parameters including average power consumption and propagation delay time are linked. To do this, the required mathematical backgrounds are presented in this study.ConclusionThe optimum values for the design parameters of MOSFETs channel widths and power supply are discovered. Based on them the power delay product quantity (PDP) is 6.32 PJ at 125 MHz Clock Frequency, L = 0.18 µm, and T = 27 °C.

Multi-device task offloading with time-constraints for energy efficiency in mobile cloud computing

Nowadays, in order to deal with the increasingly complex applications on mobile devices, mobile cloud offloading techniques have been studied extensively to meet the ever-increasing energy requirements. In this study, an offloading decision method is investigated to minimize the energy consumption of mobile device with an acceptable time delay and communication quality. In general, mobile devices can execute a sequence of tasks in parallel. In the proposed offloading decision method, only parts of the tasks are offloaded for task characteristics to save the energy of multi-devices. The issue of the offloading decision is formulated as an NP-hard 0–1 nonlinear integer programming problem with time deadline and transmission error rate constraints. Through decision-variable relaxation from the integer to the real domain, this problem can be transformed as a continuous convex optimization. Based on Lagrange duality and the Karush–Kuhn–Tucker condition, a solution with coupled terms is derived to determine the priority of tasks for offloading. Then, an iterative decoupling algorithm with high efficiency is proposed to obtain near-optimal offloading decisions for energy saving. Simulation results demonstrate that considerable energy can be saved via the proposed method in various mobile cloud scenarios.

Historical based location management strategies for PCS networks

Due to the current popularity of wireless communication, personal communication service networks have attracted a lot of attention. As mobile terminals (MTs) in such networks have the ability to communicate on the move, location management (LM) is a critical issue that should be handled carefully. Managing MTs locations is to simultaneously perform two main operations, which are; location update and paging. A good LM strategy maintains both operations with the minimum time and signaling penalties. Although several LM strategies have been introduced, they still suffer from several drawbacks. This paper introduces three novel LM strategies, which are; historical based location management (HBLM), direction based location management (DBLM) and trajectory based location management (TBLM). TBLM strategy is based on geographical position of MTs, while HBLM and DBLM are based on geographical position of MTs as well as time aspects. Visited locations are saved in MT's internal cache in the form of cell identifier as well as the corresponding time interval. Location tracking is fully supervised by the MT's current visitor location register (VLR). On the other hand, the collected location information in MT's cache is sent to VLR when MT passed through a previously defined number of cells or when a previously defined number of time periods has elapsed. In HBLM, paging is done according to the historical movements saved in VLR, while DBLM takes also MT's movement direction into consideration while in TBLM, paging is done according to the historical trajectories that MTs are used to follow. Experimental results have shown that the proposed LM strategies significantly improve MTs' tracking process as they introduce the minimum signaling penalty (for paging and registration) with an acceptable paging time delay compared with recent LM strategies.

Partograma con curvas de alerta en pacientes del cono sur de Lima

Durante los años 1991 y 1992, en el Hospital "María Auxiliadora" se escogió 1500 parturientas, de las cuales 587 fueron nulíparas y 913 multíparas. A todas se les aplicó los siguientes criterios: cronología del embarazo entre 37 y 41 semanas, ausencia de patología, parto de inicio y evolución espontánea, no medicación durante el parto, pelvis normal, presentación cefálica y recién nacido de 2500 a 4000 gr con score de Apgar mayor de 6 al nacer. Después de aplicar estos criterios, reunimos finalmente 317 nuliparas (209 con membranas íntegras y 108 con membranas rotas) y 306 multíparas (231 con membranas íntegras y 75 con membranas rotas). Todas las pacientes estuvieron en decúbito durante el trabajo de parto y fueron controladas en el centro obstétrico utilizando el partograma diseñado por el CLAP y cuidando de hacer los registros gráficos a partir de los 4-5 cm de dilatación cervical en adelante. Los datos de la dilatación del cuello uterino en relación al tiempo fueron procesados en computadora y se calculó el percentil 10, o sea el tiempo máximo aceptable que demora la dilatación cervical de centímetro a centímetro hasta el período expulsivo, y con ello se construyó las curvas de alerta para cada uno de los cuatro subgrupos. La pendiente seguida en el proceso de dilatación del cuello uterino es la misma en nuestras parturientas que las reportadas por el CLAP, pero los tiempos están recostados un poco hacia la derecha, particularmente en el subgrupo de nulíparas con membranas íntegras.

A Novel Encryption Scheme for Digital Image - Based on One Dimensional Logistic Map

In this paper, an implementation of digital image encryption scheme based on one dimensional logistic map is proposed. The chaotic cryptography technique concentrates in general on the symmetric key cryptographic technique. In the proposed algorithm, a random key table lookup criterion was combined with a one-dimensional chaotic map were used for high degree 2-stage security image encryption while maintaining acceptable overhead delay time. The proposed algorithm is based on image row shuffling and pixel-wise XOR encryption. To increase the security of row shuffling variable rotation and inversion were applied to each shuffled row, based on the difference between old and new row location. The experimental results showed that the proposed algorithm is effective and applicable. The combination of logistic map and key table lookup shows advantages of large random key space and high-level of security. The resulting cipher image is suitable for practical use in secure image storing and transmission.

Perception of delay time of head movement in using an acoustical telepresence robot: TeleHead

We built an acoustical telepresence robot, TeleHead, which has a user-like dummy head and is synchronized with the user’s head movement in real time. We are trying to clarify the effects of reproducing head movement. In this paper, we evaluate the sense of incongruity induced by the delay time in reproducing head movement. The results indicate that whether users feel the delay or not depends on their spatial perception. Therefore, acceptable delay time can be calculated from the user’s localization accuracy and head movement speed. Even under the strictest condition, i.e. high-speed head movements, using white noise makes it easier to localize sounds and roughly about 40-ms delay may be acceptable. Moreover, in conversational situations, 80-ms delay is acceptable.

Macroslip detection and clamping force control for a metal V-belt continuously variable transmission

In this paper, a macroslip detection method is proposed for a metal V-belt continuously variable transmission, and a clamping force control strategy is suggested on the basis of a macroslip detection method. Using the rotational accelerations of the primary and secondary pulleys, the velocity of the secondary pulley and the speed ratio of the continuously variable transmission variator, observation signals are defined. The characteristics of the observation signals are investigated by simulations in a vehicle-driving environment. It is found that two observation signals became unsynchronized when macroslip occurs. Considering the oscillations of the acceleration signal and the noise from the sensors or the differentiating process, a signal-processing method for the observation signals is suggested. Based on the signal-processing results, a variable called the ‘amplitude difference rate’ is introduced for slip evaluation. A macroslip detection method that uses the amplitude difference rate is proposed. The effectiveness of the macroslip detection method is validated by experiments. It is found from the experiments that the proposed method can effectively detect macroslip with an acceptable time delay. In addition, a clamping force control strategy based on the macroslip detection method is developed. In this strategy, the clamping force is maintained at a minimum value with a safety factor of 1 in normal driving conditions but an additional clamping force is applied when macroslip is detected. It is found from the simulation results that macroslip is eliminated by clamping force control. It is expected that the efficiency of the continuously variable transmission system can be improved by reducing the marginal clamping force using the proposed macroslip detection method and the clamping force control strategy.

Implementation for Two-Stage Hybrid Decoding for Low Density Parity Check (LDPC) Codes

ABSTRACT LDPC codes are gaining high attention in Channel Coding field these days. However, one of the main problems facing usage of these codes in communication systems is the high complexity decoding scheme that results in high decoding delay. Such delay is not acceptable in some applications that depend on time such as video transmission. This paper presents hardware implementation technique for Two-Stage Hybrid decoder resulting in better complexity and delay. Also, it shows comparison between soft, hard and hybrid decoding techniques in terms of memory usage, and delay time as to be used for real implementation for some applications such as DVB-S2. Keywords Channel Coding, LDPC, VHDL, Hybrid decoding. 1. INTRODUCTION The first Low-Density Parity Check Code (LDPC) was discovered by Gallager [1], [2] in 1960s where this code proved the extraordinary performance with iterative decoding that was very close to Shannon limit which is difficult to reach. LDPC codes are used in many applications such as DVB-S2 [3], which is a standard for Digital Video Broadcasting–Satellite-Second Generation because of its excellent Bit Error Rate (BER) performance. These codes are expected to be included in many future standards as well as to replace many existing channel coding techniques. There are many types of LDPC decoding algorithms that have good performance with acceptable delay time. These algorithms can be classified into soft-decision decoding algorithm such as the Sum-Product Algorithm (SPA) and hard-decision decoding algorithm such as Bit-Flipping (BF) algorithm which was discovered by Gallager. The Bit-Flipping algorithm has many modified versions [4], [5], [6] that have better BER performance compared to the original Bit-Flipping algorithm. The good BER performance of SPA comes on the expense of the high complexity which increases the delay time for the used design. Such high delay is considered as a drawback for some applications especially for those who are greatly affected by the delay such as video and audio transmission. On the other side, hard decision such as Bit Flipping algorithm and its modified versions have limited BER performance with lower complexity and delay time if compared to (SPA). So, Two-Stage Hybrid decoding algorithm proposed in [7] was used as a new decoding algorithm, where this algorithm provides a trade-off algorithm between hard and soft-decision algorithms and has better performance compared to that of BF and less complexity and delay time compared to that of SPA. This paper shows an FPGA design of the real hardware implementation for Two-Stage Hybrid decoder with comparison to SPA, and BF in terms of memory usage and delay time. The rest of the paper is organized as follows. Section (2) presents the background on SPA and BF algorithms. These algorithms provide the basis for the Two-Stage Hybrid decoding. Also, this section presents the existing Two-Stage Hybrid algorithm and how it is composed of SPA as the first stage and BF as the second stage. Section (3) introduces the hardware implementation technique for the three algorithms with showing the procedure of each algorithm to compare between their performances. Section (4) includes typical simulation results for the three decoders. Also, comparison between the three decoders is shown with respect to memory usage and delay time. Finally, conclusion and future work are presented in Section (5).

Nonlinear Actuator Fault Detection for Small-Scale UASs

This paper presents a recursive strategy for online detection of actuator faults on a unmanned aerial system (UAS) subjected to accidental actuator faults. The proposed detection algorithm aims to provide a UAS with the capability of identifying and determining characteristics of actuator faults, offering necessary flight information for the design of fault-tolerant mechanism to compensate for the resultant side-effect when faults occur. The proposed fault detection strategy consists of a bank of unscented Kalman filters (UKFs) with each one detecting a specific type of actuator faults and estimating corresponding velocity and attitude information. Performance of the proposed method is evaluated using a typical nonlinear UAS model and it is demonstrated in simulations that our method is able to detect representative faults with a sufficient accuracy and acceptable time delay, and can be applied to the design of fault-tolerant flight control systems of UASs.

NIOSH-Sponsored Research in Through-the-Earth Communications for Mines: A Status Report

This paper presents the results of recent contractual research sponsored by the National Institute for Occupational Safety and Health that aimed at demonstrating the feasibility of through-the-earth (TTE) wireless communication in mining. TTE systems, developed by five different contractors, are discussed with a focus on technical approach, prototype hardware, and field test results. System features include both magnetic and electric field sensing, loop and line antennas, digital and analog processing, noise filtering and cancelation, and direction finding. The systems were demonstrated at commercial mine sites. The results of these tests are characterized by transmission range and power levels. This paper concludes with a discussion of issues that remain to be resolved as TTE communications are implemented. These include text versus voice format, acceptable time delays, portability, ease of deployment, an interface with existing communications systems, permissibility, and the effect of geological variations.

Proposed Hybrid MAC Layer Design for Priority Application Usage in Wireless Sensor Network (WSN)

The design of Medium Access Control (MAC) layer in Wireless Sensor Network (WSN) is very important because it gives significant impact in network performance especially in term of energy consuming. Contention Access method which is Carrier Sense Multiple Access (CSMA) will encounter collision problem when more than one node want to access the network simultaneously. Meanwhile, the issue in slotted access which is Time Division Multiple Access (TDMA) is channel utilization when the usage of the slot is neglected and wasted in transmission network. In this paper, we propose a hybrid MAC that combines both strengths of CSMA and TDMA in one protocol while avoiding their weaknesses to improve the network performance. The simple and efficient transmission in CSMA method will be used in neighbor discovery (ND) and slot allocation (SA) process. For data transmission, non collision transmission method which is TDMA will be used and it will be changed to CSMA depending on the contention level of the channel. This proposed protocol is suitable for priority application usage where the important information will arrived at the destination in acceptable delay time.

Acceptable reperfusion delay to prefer primary angioplasty over fibrin-specific thrombolytic therapy is affected (mainly) by the patient's mortality risk: 1 h does not fit all

The mortality benefit of primary percutaneous coronary angioplasty (PPCI) is time-dependent. We explored the relationship between risk and PPCI delay, adjusted for the delay at presentation, which leads to equivalent 30-day mortality between PPCI and fibrin-specific thrombolytic therapy (TT). Sixteen randomized trials were analysed. The mortality rate in the TT arm was interpreted as a proxy for mortality risk. We calculated the PPCI-related delay as the difference between 'door-to-balloon minus door-to-needle' time and PPCI survival benefit as 30-day mortality after TT minus 30-day mortality after PPCI. Baseline mortality risk (P = 0.004), PPCI delay (P = 0.006), and presentation delay (P = 0.03) were correlated with 30-day survival benefit of PPCI. By the regression analysis, the following equation: Z = 0.59X - 0.033Y - 0.0003W - 1.3 (where Z is the absolute reduction in mortality of PPCI over TT, X the mortality risk, Y the PPCI-delay, and W the presentation delay), can be calculated. According to this equation, acceptable angioplasty-related delay shows a wide range based mainly on the different risk profiles. Baseline mortality risk of ST elevation myocardial infarction patients is a major determinant of the acceptable time delay to choose the most appropriate therapy. Although a longer delay lowers the survival advantage of PPCI, a longer PPCI-related delay could be acceptable in high-risk STEMI patients.

Appointment Delay among Patients Attending Endocrinology Outpatient Clinic of Al-Qatif Central Hospital, Kingdom of Saudi Arabia

Patient’s appointment is a fixed mutual agreement between patient and any health care giver to obtain the required medical services that suit his/ her health needs. Appointment delays in outpatient clinics are the most important cause for patients’ dissatisfaction due to the complications that might develop during the wait time and consequently affecting their health status. The present study aimed to measure the appointment time from referral from primary health care centers to get the first appointment for patients cared for the most common diseases in the endocrinology o utpatient clinic of Al-Qatif Central Hospital, and study reasons and effect of delayed appointment on patients. It is a cross- sectional descriptive study. The target population was medical records and database of 200 patients, all the working staff, and patients attended the study clinic during the year 2008. Results revealed that 60.5% of the patients had delayed appointment, while 39.5% had no delayed appointment. The acceptable appointment time delay for diabetes mellitus, hypothyroidism and hyperthyroidism were ( X = 55± 8.66, 95 ± 5.00 and 19 ± 4.35 days respectively) in comparison to the current appointment time delay ( X =118.3± 81.0, 113.6± 70.4 and 87.9± 49.7 days respectively). Most of the patients with delayed appointment were dissatisfied (74.4%) compared to only 67% of those with no delayed appointment. Also, 22.3% of the patients with delayed appointment perceived that their health status was affected to a great extent in comparison to only 10.1% of those with no delayed appointment. Among the reasons mentioned by the working staff for delayed appointment were increased number of “no show” patients, population served by the study hospital, and follow up visits (83.3% each). Accordingly, the present study recommended availability of a center for diagnosis and treatment of diabetes mellitus in addition to the outpatient clinic of the study hospital; developing a system for reminding patients with the date of appointment e.g. SMS, telephone call,…etc; and establishing a prioritizing system for appointments based on emergency of the conditions.

Non small cell lung cancer: Do delays in diagnosis and treatment affect outcome

17559 Background: Delay in management of patients with non-small cell lung cancer (NSCLC) may reduce survival and quality of life. However, the minimal acceptable time delay from suspicion to treatment and factors affecting delay has not been determined. Methods: All patients with NSCLC between February 1999 and December 2005 at the Hines VA were identified and specific key dates during each patient's management course were recorded. The outcome events were death and type of intervention: definitive surgery or palliation. A retrospective cohort analysis was performed. Given a difference in expected survival based upon the disease stage we stratified patients into two groups: one group composed of patients with stage I/II disease and the other group with stage III/IV disease. Within each stratum we conducted univariate and multivariate analysis by determining the relative risk for the chosen outcome based upon the presence or absence of several potential predictors of outcome: age, race, co-morbidities (Charleson Index), presence or absence of a primary care provider and substance abuse. Results: The relative risk of death with stage I/II disease diagnosed ≤ 30 days compared to > 30 days was 0.75 (95% CI: 0.40 -1.46) and was 1.72 (95% CI: 1.28–2.31) for those with stage III/IV. The Charleson index (1–2) was associated with reduced survival (RR=1.52; 95% CI: 1.03–2.27). Lack of a primary care physician was associated with worse survival (RR=1.55; 95% CI: 1.09–1.58). Conclusions: Timely diagnosis in patients with late stage disease, patient morbidity and lack of a primary care physician was associated with worse survival. No significant financial relationships to disclose.

Information foraging on the web: The effects of “acceptable” Internet delays on multi-page information search behavior

Web delays are a persistent and highly publicized problem. Long delays have been shown to reduce information search, but less is known about the impact of more modest “acceptable” delays — delays that do not substantially reduce user satisfaction. Prior research suggests that as the time and effort required to complete a task increases, decision-makers tend to reduce information search at the expense of decision quality. In this study, the effects of an acceptable time delay (seven seconds) on information search behavior were examined. Results showed that increased time and effort caused by acceptable delays provoked increased information search.

Are Displaced Talar Neck Fractures Surgical Emergencies? A Survey of Orthopaedic Trauma Experts

Displaced talar neck fractures are relatively rare injuries with potentially serious long-term morbidity. Expedient treatment has long been held as a treatment principle. The purpose of this study was to assess the current state of practice of treating displaced talar neck fractures by recognized orthopaedic trauma experts working at level 1 trauma centers. A group of expert orthopaedic trauma surgeons were surveyed to determine what they considered "the maximal acceptable time delay from injury to the operating room representing the minimal standard of care at a level 1 trauma center for a displaced talar neck fracture?" Each survey recipient had been selected as a moderator at a national orthopaedic trauma meeting during the past 5 years. Eighty-nine of 109 (82%) responded to the survey. For a displaced talar neck fracture, 60% of respondents stated that treatment after 8 hours is acceptable, with 46% percent of respondents stating that treatment at or after 24 hours is acceptable. These results indicate that most expert orthopedic trauma surgeons do not believe that an immediate operation is necessary to adequately treat a displaced talar neck fracture.

Preemptive priority policy for hot lots transport services in 300mm semiconductor foundry

Highly automated material handling is one of the most concerns to foundry practitioners because efficient manual operations and coordination have been the core competence in 300mm manufacturing. Especially, one of the critical problems is how to provide an almost no-wait transport for hot lots in an automatic material handling environment. However, there is no effective method for hot lots handling in 300mm Overhead Hoist Transport (OHT) intrabay operation. This paper proposes an effective OHT dispatching method, Preemptive Priority Policy (PPP), to provide the transport services for hot lots against the normal lots transport requirements under 300mm frequently blocking transportation situation. The objective is to minimize the transport delay of hot lots and to convey our idea for hot lots transport services. Simulation experiments based on realistic data from a 300mm wafer foundry are conducted. Numerical results demonstrate that the PPP method can effective expedite the movement of the hot lots with acceptable time delay on normal lots, which is very useful to streamline the shop floor operations, like scheduling and dispatching, for eliminating time delays of hot lots in an automated environment. This can help fab managers for more precisely lots management and automated material handling system (AMHS) control.

Stability of major ions and sampling variability in daily bulk precipitation samples

Daily (24-h) precipitation samples were collected in four parallel bulk samplers in order to examine differences between parallel samples and the maximum acceptable time delay between sampling and analysis. After an immediate analysis, the samples were stored at +4°C over a seven-week time period to regularly examine the changes in ionic composition. The experiment was carried out in Helsinki, Finland, over the period from June 1997 to June 1998, with six rain events collected. Electrical conductivity, pH and the concentrations of the major ions Na +, NH 4 +, K +, Mg 2+, Ca 2+, Cl −, NO 3 − and SO 4 2− were studied. No significant differences between the parallel samplers were observed showing that dry deposition does not usually result in increased variability for 24-h bulk sampling due to the short dry period exposed. Sodium, potassium, magnesium, calcium, chloride, nitrate and sulphate concentrations remained constant for at least seven weeks. The electrical conductivity decreased by up to 30% and the pH increased by up to 0.3 pH unit, in thunderstorm sample even 1 pH unit, after six days. The ammonium concentration had a slight decreasing trend in all rain events and in some events the concentration decreased by upto 25% during the seven weeks storage. To achieve as precise results as possible for pH, electrical conductivity and ammonium the recommended maximum time delay between sampling and analysis is one week.

A fault-tolerant architecture for ATM networks

The asynchronous transfer mode (ATM) is the transfer mode recommended for the broad integrated service digital network (B-ISDN) by ITU-T. In this paper, we propose a self-routing fault-tolerant switching architecture for ATM networks. The proposed architecture uses subswitches and extra links to provide alternative paths; hence, can tolerate multiple faults. Analytical results show that the total number of redundant paths increases exponentially as the size of the network increases. A simulation model is developed. Simulation results indicate that the proposed architecture is much more fault-tolerant and cost-effective than those architectures found in the literature. Simulation results also illustrate that the proposed architecture still maintains a high throughput with an acceptable cell delay time, even when the number of faulty elements increases.