Time Code Research Articles

A Thermo-Hydraulic Tool for Automatic Virtual Hazop Evaluation

Abstract Development of complex lubrication systems in the Oil&Gas industry has reached high levels of competitiveness in terms of requested performances and reliability. In particular, the use of HazOp (acronym of Hazard and Operability) analysis represents a decisive factor to evaluate safety and reliability of plants. The HazOp analysis is a structured and systematic examination of a planned or existing operation in order to identify and evaluate problems that may represent risks to personnel or equipment. In particular, P&ID schemes (acronym of Piping and Instrument Diagram according to regulation in force ISO 14617) are used to evaluate the design of the plant in order to increase its safety and reliability in different operating conditions. The use of a simulation tool can drastically increase speed, efficiency and reliability of the design process. In this work, a tool, called TTH lib (acronym of Transient Thermal Hydraulic Library) for the 1-D simulation of thermal hydraulic plants is presented. The proposed tool is applied to the analysis of safety relevant components of compressor and pumping units, such as lubrication circuits. Opposed to the known commercial products, TTH lib has been customized in order to ease simulation of complex interactions with digital logic components and plant controllers including their sensors and measurement systems. In particular, the proposed tool is optimized for fixed step execution and fast prototyping of Real Time code both for testing and production purposes. TTH lib can be used as a standard SimScape-Simulink library of components optimized and specifically designed in accordance with the P&ID definitions. Finally, an automatic code generation procedure has been developed, so TTH simulation models can be directly assembled from the P&ID schemes and technical documentation including detailed informations of sensor and measurement system.

Optimizing Aqua Splicer Parameters for Lycra−Cotton Core Spun Yarn Using Taguchi Method

In this paper, optimization of the aqua splicer parameters viz opening time, splicing time, feed arm code (i.e. splice length) and duration of water joining was carried out for 37 tex lycra−cotton core spun yarn for better retained splice strength (RSS%), splice abrasion resistance (RYAR%) and splice appearance (RYA%) using Taguchi experimental design. It is observed that as opening time, splicing time and duration of water joining increase, the RSS% and RYAR% increases, whereas increase in feed arm code leads to decrease in both. The opening time and feed arm code do not have significant effect on RYA%. The optimum RSS% of 92.02 % was obtained at splicing parameters of 350 ms opening time, 180 ms splicing time, 65 feed arm code and 600 ms duration of water joining.

High-precision two-way optic-fiber time transfer using an improved time code.

We present a novel high-precision two-way optic-fiber time transfer scheme. The Inter-Range Instrumentation Group (IRIG-B) time code is modified by increasing bit rate and defining new fields. The modified time code can be transmitted directly using commercial optical transceivers and is able to efficiently suppress the effect of the Rayleigh backscattering in the optical fiber. A dedicated codec (encoder and decoder) with low delay fluctuation is developed. The synchronization issue is addressed by adopting a mask technique and combinational logic circuit. Its delay fluctuation is less than 27 ps in terms of the standard deviation. The two-way optic-fiber time transfer using the improved codec scheme is verified experimentally over 2 m to100 km fiber links. The results show that the stability over 100 km fiber link is always less than 35 ps with the minimum value of about 2 ps at the averaging time around 1000 s. The uncertainty of time difference induced by the chromatic dispersion over 100 km is less than 22 ps.

A Novel Wireless Statistical Division Multiplexing Communication System and Performance Analysis

This paper proposes a new wireless statistical division multiplexing (SDM) communication system, which is based on the two-input and two-output wireless communication experimental platform constructed and presented in our previous work. This novel system aims to transmit source signals simultaneously in the same frequency band over wireless channel and recovers the source signals at the receiver by utilizing the statistical characteristics of source signals and broadcasting characteristics of wireless channel. Therefore, the spectrum efficiency of SDM system is high compared to those of time division multiplexing (TDM), frequency division multiplexing (FDM), and code division multiplexing (CDM) systems, in which TDM, FDM and CDM signals are limited in time interval, frequency band and code. Taking advantage of the statistical properties of transmitted source signals, the SDM system can easily recover or retrieve them through the blind source separation (BSS) techniques at the receiver. This paper first introduces the system model of SDM briefly, but the main purpose is to analyze the performance of it including the relationship between the separation quality and the characteristics of source signals, the power of transmitters and separation algorithms. The performance validity and corresponding analysis are confirmed and performed through realistic experiments.

Are we following the WHO recommendations for surgical scrubbing?

Surgical site infections have an incidence as high as 10%. To reduce this, the World Health Organisation (WHO) recommends guidelines for surgical scrubbing. We assessed adherence of surgical staff scrub practice before gowning to current WHO recommendations. A prospective study conducted in operation theatres in a university hospital. Participants comprised of consultant surgeons, trainees and scrub nurses. Variables included staff grade, scrub order, length of scrub time and appropriate dress code. Data were collected anonymously and analysed. We assessed 303 surgical scrub-episodes (95 scrub nurses, 123 trainees and 85 consultant surgeons). Mean time for first scrub of the day was 239 s, SD = 99, 95% CI 218, 259 and range = 530 (scrub nurses = 297 s, trainees = 204 s, consultant surgeons = 202 s). Mean time for subsequent scrubs was 161 s, SD = 63, 95% CI 152, 170, range = 312 (scrub nurses = 184 s, trainees = 158 s, consultant surgeons = 143 s). Statistical significance was found between staff grades based on scrub time, with WHO breaches in remaining variables. No written local guidelines on hand scrubbing exist in the hospital and staff were unaware of WHO guidelines. In this study, mean scrub times were less than WHO guidelines with significant variation in practice across grades of staff. Clear written guidelines are needed.

Improved perception-based spiking neuron learning rule for real-time user authentication

Spiking neural networks (SNNs) have been highly successful in spatiotemporal pattern recognition. As one of the most efficient supervised learning algorithms in spike sequences learning, the perceptron-based spiking neuron learning rule (PBSNLR) still has a relatively high computational complexity, which is difficult to use in a real-time system. In this paper, a novel method is presented to improve PBSNLR׳s efficiency without reducing its accuracy, and this method is applied to solve user authentication problem in real time. In our method, a user׳s behavioral biometric of sliding dynamic and finger pressure are selected as spatiotemporal features to recognize the user׳s identity. The temporal feature is obtained by the time coding of SNNs and the spatial feature is represented by the neurons׳ relative positions. Comprehensive experimental results demonstrate that our improved algorithm outperforms the traditional PBSNLR in terms of efficiency and exhibits excellent performance when identifying users of touch screen devices.

Protocol for the process evaluation of a complex intervention designed to increase the use of research in health policy and program organisations (the SPIRIT study).

BackgroundProcess evaluation is vital for understanding how interventions function in different settings, including if and why they have different effects or do not work at all. This is particularly important in trials of complex interventions in ‘real world’ organisational settings where causality is difficult to determine. Complexity presents challenges for process evaluation, and process evaluations that tackle complexity are rarely reported. This paper presents the detailed protocol for a process evaluation embedded in a randomised trial of a complex intervention known as SPIRIT (Supporting Policy In health with Research: an Intervention Trial). SPIRIT aims to build capacity for using research in health policy and program agencies.MethodsWe describe the flexible and pragmatic methods used for capturing, managing and analysing data across three domains: (a) the intervention as it was implemented; (b) how people participated in and responded to the intervention; and (c) the contextual characteristics that mediated this relationship and may influence outcomes. Qualitative and quantitative data collection methods include purposively sampled semi-structured interviews at two time points, direct observation and coding of intervention activities, and participant feedback forms. We provide examples of the data collection and data management tools developed.DiscussionThis protocol provides a worked example of how to embed process evaluation in the design and evaluation of a complex intervention trial. It tackles complexity in the intervention and its implementation settings. To our knowledge, it is the only detailed example of the methods for a process evaluation of an intervention conducted as part of a randomised trial in policy organisations. We identify strengths and weaknesses, and discuss how the methods are functioning during early implementation. Using ‘insider’ consultation to develop methods is enabling us to optimise data collection while minimising discomfort and burden for participants. Embedding the process evaluation within the trial design is facilitating access to data, but may impair participants’ willingness to talk openly in interviews. While it is challenging to evaluate the process of conducting a randomised trial of a complex intervention, our experience so far suggests that it is feasible and can add considerably to the knowledge generated.Electronic supplementary materialThe online version of this article (doi:10.1186/s13012-014-0113-0) contains supplementary material, which is available to authorized users.

Threaded Space Time Code Design for CPM with Joint Decoding

In the letter, a system of continuous phase modulation (CPM) with threaded space time codes (TSTC) is proposed for multiple-input multiple-output systems. In the system, source bits are coded via outer coder of Reed Solomon (RS). The codeword of which is suitable for TSTC design. Then inner coder mainly converts binary symbols into M-ary symbols for purpose of CPM. At receiver, Joint soft decoding approach is considered. Finally simulation results are provided for VBLAST, DBLAST, and TSTC as comparison.

Space–Time Coding for an Energy Harvesting Cooperative Secondary Terminal

In this letter, we consider a cognitive scenario where an energy harvesting secondary user (SU) shares the channel with a primary user (PU). The SU is equipped with two antennas. It maintains a finite capacity energy queue and two infinite capacity data queues: one for storing its own data packets and the other for storing the primary undelivered data packets. The PU com- municates with its destination whenever it has data at its queue head. During idle sessions of the PU, if the secondary energy queue maintains at least K packets, the SU employs the Alamouti coding scheme over two of its data packets. The optimization problem for secondary throughput maximization is stated under the stability of all queues in the network and a specific end-to-end queueing delay for the primary packets. Index Terms—Cooperative communications, energy harvesting, energy packets, energy queue, Markov chain, Alamouti.

수중통신에서 Zero Forcing기법을 이용한 최적의 시공간 부호화 알고리즘

수중통신에서는 다중경로로 인해 심벌간의 상호간섭이 발생하여 시스템의 성능을 저하시킨다. 최근 수중 통신시스템에서는 이러한 열악한 채널환경을 극복하고 전송률을 향상시키기 위하여 등화기 및 채널 부호화와 시공간 부호화 방식의 효율적인 연접 구조가 수중통신에서 MIMO시스템으로 응용되어 연구되고 있다. 수중 MIMO 환경에서 시공간 부호화 방식 중에서는 시공간 블록 부호화 방식과 시공간 격자 부호화 방식이 있으며, 시공간 격자 부호화 방식이 등화기 및 채널 부호화 방식에 최적이다. 따라서 본 논문에서는 다중경로 채널 환경에서 효율적인 전송을 위해 터보 Pi 부호화기를 외부부호로 사용하고, MIMO시스템에서 전송 다이버시티와 부호화이득을 동시에 가지는 시공간 격자부호를 내부부호로 구성한다. 그리고 심볼간 상호 간섭 제거를 위해 Zero Forcing 등화기법을 사용하여 수중채널에서의 시뮬레이션을 통해 성능을 확인하였다. In the underwater communication, the performance of system is reduced because of the inter-symbol interference occur by the multi-path. In the recent years, to deal with poor channel environment and improve the throughput, the efficient concatenated structure of equalization, channel codes and Space Time Codes has been studied as MIMO system in the underwater communication. Space Time Codes include Space Time Block Codes and Space Time Trellis Codes in underwater communication. Space Time Trellis Codes are optimum for equalization and channel codes among the Space Time Codes to apply in the MIMO environment. Therefore, in this paper, turbo pi codes are used for the outer code to efficiently transmit in the multi-path channel environment. The inner codes consist of Space Time Trellis Codes with transmission diversity and coding gain in the MIMO system. And Zero Forcing method is used to remove inter-symbol interference. Finally, the performance of this model is simulated in the underwater channel.

Space-Time Network Coding With Overhearing Relays

Space time network coding (STNC) is a recently proposed time-division multiple-access (TDMA)-based cooperative relaying scheme for multi-relay wireless systems, which can achieve full diversity order with low transmission delay by taking advantage of the concepts of network coding and distributed space time coding. However, STNC does not fully exploit the benefit of the broadcast nature of wireless channels, since it only allows relays to receive signals from the sources. To explore the potential capacity of STNC-based systems, in this paper, we propose a new cooperative relaying scheme, termed space-time network coding with overhearing relays (STNC-OR), by allowing each relay to collect the signals transmitted from not only the sources but also its previous relays. Then, we derive some explicit expressions for the outage probability and symbol error rate (SER) for STNC-OR with decode-and-forward relaying over independent non-identically distributed (i.n.i.d) Rayleigh fading channels. For comparison, we also derive the explicit expression of the outage probability for STNC. To further improve the performance of STNC-OR, we investigate the effect of relay ordering on the performance of STNC-OR and then present the optimal relay ordering algorithm. Further, a suboptimal relay ordering is also designed to reduce the complexity. Extensive simulation and numerical results are presented finally to validate our theoretical analysis. It is shown that the proposed STNC-OR achieves much lower outage probability and SER than STNC and traditional pure TDMA relaying schemes.

MIMO 수중통신에서 최적의 터보 등화 기법

수중에서의 음향 통신의 성능은 신호의 다중경로 전달과정에 의해 발생하는 지역 확산 현상으로 인하여 인접간섭의 영향을 받는다. 그리고 음파를 이용한 주파수의 제한으로 인하여 낮은 전송 속도로 통신을 한다. 따라서 전송속도의 향상과 함께 인접간섭을 제거하기 위하여 수중 통신에 적합한 시공간 부호화 기술과 등화기 기술, 채널 부호화 기술이 필요하다. 본 논문에서는 이러한 기술들을 시뮬레이션을 통하여 MIMO 수중 통신 시스템에서 최적의 터보 등화 기법을 이용한 복호구조를 제안한다. 각 모듈별 시뮬레이션을 통한 성능결과 본 논문에서 제안한 계층적 시공간 부호화 방식 기반의 터보 등화 기법을 이용하면 일반적인 수중 통신 보다 성능이 우수함을 알 수 있다. The performance of underwater acoustic(UWA) communication system is sensitive to the Inter-Symbol Interference(ISI) due to delay spread develop of multipath signal propagation. And due to limited frequency using acoustic wave, UWA is a low transmission rate. Thus, it is necessary technique of Space-time code, equalizer and channel code to improve transmission speed and eliminate ISI. In this paper, UWA communication system were analyzed by simulation using these techniques. In the result of simulation, the proposed Turbo Equalization method based on layered Space Time Codes has improved performance compared to conventional UWA communication.

Effective Capacity Maximization in Multirelay Networks With a Novel Cross-Layer Transmission Framework and Power-Allocation Scheme

Effective capacity (EC) is a valuable metric in investigating the impact of the physical-layer infrastructure on the quality of service (QoS) of the data link layer. By means of the EC, this paper provides a link-layer look at the concept of multirelaying transmission. A closed-form expression for the EC of a multirelay network is derived to simplify the computation of this quantity. It is shown that increasing the number of relays leads to an unavoidable reduction in EC. Some techniques such as best relay selection (BRS) and distributed space-time coding (DSTC) are used to solve this problem. It is found that the EC performance of BRS, DSTC, and direct transmission schemes extremely depends on the amount of QoS exponent θ. Inspired by this dependence, a novel interesting cross-layer relaying transmission framework is introduced, in which the best scheme of transmission is selected for maximizing the EC, according to the amount of θ and the channel gain. Then, by the goal of EC maximization under a given θ, a cross-layer fixed power-allocation (PA) algorithm is proposed based on the particle swarm optimization (PSO) algorithm. The numerical results validate our analytical outcomes and evaluate our proposed algorithms. The complexity of the proposed algorithms is analyzed at the end of this paper.

Comparison of syndromic methods for correcting block positional and timing codes

На основі статистичних даних якісних характеристик корегуючих блокових кодів позиційного і таймерного кодування перевірено умови належності каналів міської телефонної мережі (МТМ) до каналів моделі Гілберта. Сформульовані переваги та недоліки синдромних методів виявлення та виправлення помилок при позиційному та таймерному кодуванні. Синтезовані алгоритми, забезпечуючі збільшення швидкості передачі при високій якості.

Inhibition does not affect the timing code for vocalizations in the mouse auditory midbrain.

Many animals use a diverse repertoire of complex acoustic signals to convey different types of information to other animals. The information in each vocalization therefore must be coded by neurons in the auditory system. One way in which the auditory system may discriminate among different vocalizations is by having highly selective neurons, where only one or two different vocalizations evoke a strong response from a single neuron. Another strategy is to have specific spike timing patterns for particular vocalizations such that each neural response can be matched to a specific vocalization. Both of these strategies seem to occur in the auditory midbrain of mice. The neural mechanisms underlying rate and time coding are unclear, however, it is likely that inhibition plays a role. Here, we examined whether inhibition is involved in shaping neural selectivity to vocalizations via rate and/or time coding in the mouse inferior colliculus (IC). We examined extracellular single unit responses to vocalizations before and after iontophoretically blocking GABAA and glycine receptors in the IC of awake mice. We then applied a number of neurometrics to examine the rate and timing information of individual neurons. We initially evaluated the neuronal responses using inspection of the raster plots, spike-counting measures of response rate and stimulus preference, and a measure of maximum available stimulus-response mutual information. Subsequently, we used two different event sequence distance measures, one based on vector space embedding, and one derived from the Victor/Purpura Dq metric, to direct hierarchical clustering of responses. In general, we found that the most salient feature of pharmacologically blocking inhibitory receptors in the IC was the lack of major effects on the functional properties of IC neurons. Blocking inhibition did increase response rate to vocalizations, as expected. However, it did not significantly affect spike timing, or stimulus selectivity of the studied neurons. We observed two main effects when inhibition was locally blocked: (1) Highly selective neurons maintained their selectivity and the information about the stimuli did not change, but response rate increased slightly. (2) Neurons that responded to multiple vocalizations in the control condition, also responded to the same stimuli in the test condition, with similar timing and pattern, but with a greater number of spikes. For some neurons the information rate generally increased, but the information per spike decreased. In many of these neurons, vocalizations that generated no responses in the control condition generated some response in the test condition. Overall, we found that inhibition in the IC does not play a substantial role in creating the distinguishable and reliable neuronal temporal spike patterns in response to different vocalizations.

Building a high quality medical data architecture for multiple uses in an integrated health care environment

Objective: The aim was to create a reliable information provisioning system in healthcare for both care and research processes, based on existing data standards and standardized electronic messages. The research question is: How can a Clinical Data Ware House (CDWH) be developed for standardized basic patient data, generic nursing data and data about oncology nursing, allowing management of Electronic Health Record data, electronic data exchange and data analytics? Materials and methods: The main instrument used was the Detailed Clinical Model (DCM) data standardization approach. Further, data communication utilized HealthLevel7v3 (HL7v3) messages, transported by Mirth Connect. In an incremental, design-oriented research project, CDWH-prototypes were constructed using Enterprise Architect, a HL7v3 generator plug-in, SQL Server technology and PostgreSQL-based CDWH-technology. Results: The project resulted in 16 existing DCMs selected and 6 new DCMs defined. From those DCMs, a HL7v3 message structure was generated and a CDWH created. Implementing specialized Data Marts (DM) a connection between the CDWH and one Electronic Health Record system was built. Discussion: Detailed Clinical Models improve data quality, yet building them consumes time and resources. Some required data codes could not be identified in time and dummy codes were used instead. The existence of unstructured medical data in legacy systems may proof to be an obstacle in the future. Conclusion: The project shows that using Detailed Clinical Models as the sole source for system development leads to a sound design for a CDWH and HL7v3 messages, supporting a standards based health information system, suitable for multiple uses.

Smart IEEE–1588 GPS Clock Emulator for Cabled Ocean Sensors

Today, cabled seafloor observatories are installed at many sites around the globe, gathering different types of sensors in the marine environment where a Global Positioning System (GPS) signal is not accessible. Accurate time marking of ocean sensor data is highly important in many marine applications. This paper presents a smart GPS emulator based on the IEEE-1588 Precision Time Protocol (PTP). The device was designed and implemented to be able to provide accurate timing data (trigger + time code) to any ocean sensor as a broadband seismometer. In this case, accurate location and magnitude of a detected earthquake are dependent on the accuracy of the data time marks. The performance of time synchronization is tested, using a commercial broadband seismometer, and the results are presented. These tests are based on a comparison of the synchronization trigger between master and slave clocks as well as the analysis of the data acquired by the seismometer. The work presented here leads to an improved performance of the ocean-bottom seismometers as well as tsunami warning systems.

Caring for those who die at home: the use and validation of ‘Care Of the Dying Evaluation’ (CODE) with bereaved relatives

BackgroundAs well as facilitating patients’ wish to die at home, evaluating quality of care in this setting is essential. Postbereavement surveys with family members represent one assessment method. ‘Care Of...

A robust adaptive array beamformer using particle swarm optimization for space–time code division multiple access systems

An adaptive beamformer often suffers from severe performance degradation when a mismatch exists in the steering vector of interest. In this study, a new approach to the robust adaptive beamforming technique is proposed based on minimum variance distortionless response (MVDR) for space–time systems. The proposed method combines particle swarm optimization (PSO) and Taylor series expansion to enable the use of direction-of-arrival (DOA) estimation. Taylor series expansion can be robust to pointer errors for the presumed steering vector. However, the Taylor approach is easily trapped at a local minimum, causing errors in DOA estimation. Therefore, a more accurate DOA estimate is necessary for MVDR beamforming. To resolve this problem, a DOA estimation approach featuring a high resolution and low computational load is presented in this paper. An initial DOA estimate is first determined using a PSO estimator. Next, the predominant DOA estimate is sent to the Taylor series expansion-based estimator to form an estimate. Several simulation results are provided to demonstrate the effectiveness of the proposed approach.

CARING FOR THOSE WHO DIE AT HOME – THE USE AND VALIDATION OF ‘CARE OF THE DYING EVALUATION’ (CODE) WITH BEREAVED RELATIVES

Background‘CODE’ is a 40-item self-completion post-bereavement questionnaire, focused on the last days of life and based on key components of best practice for care of the dying. CODE is a...