bluuebunny/crossref_metadata_2025 huggingface dataset:
How many rodents die on the road? Biological and methodological implications from a small mammals’ roadkill assessment on a Spanish motorway
Authors: Ruiz‐Capillas Pablo , Mata Cristina , Malo Juan E.
Published: December 2014

Some small mammal species use road verges as a habitat for sheltering. As a result, their populations suffer mortality from roadkill in an unknown extent. We analysed the road mortality of small mammals and the population impact of roadkill on wood mouse along 1 year on a 4‐km motorway stretch. To account for potential bias in carcass sampling, we conducted walking surveys with the traffic interrupted and we performed three carcass persistence experiments to estimate total number of roadkills. The estimations were contrasted with previous studies and the population abundance on the road verges. The spatial pattern and the effects of seasonality and traffic volume on roadkill were analysed. We recorded 84 rodent carcasses with a mean carcass persistence of 6.65 days (SE = 0.41). The estimations of roadkill ranged between 190.2 and 238.3 individuals km−1year−1, with a mean value close to a monthly 6 % mortality for the most common specie. Roadkill was more frequent during the hottest and driest months, and showed a unimodal relation with traffic peaking at 8100 vehicles day−1. A spatial aggregation of roadkill was detected with 80–190 m clustering. Our results suggest that, although rodents suffer greater roadkill mortality than previously reported, it affects a small percentage of the wood mouse population in our study area. This source of mortality is unlikely to affect population viability in the short term. Our results show that roadkill surveys should be specifically designed for small mammals to have a more accurate analysis of the effects of roadkill on their populations.
Individual trans 18:1 Isomers are Metabolised Differently and Have Distinct Effects on Lipogenesis in 3T3‐L1 Adipocytes
Authors: Vahmani P. , Meadus W. J. , Turner T. D. , Duff P. , Rolland D. C. , Mapiye C. , Dugan M. E. R.
Published: December 2014

The objective of this research was to study the metabolism of individual trans fatty acids (FAs) that can be found in ruminant fat or partially hydrogenated vegetable oils (PHVO) and determine their effects on FA composition and lipogenic gene expression in adipocytes. Differentiated 3T3‐L1 adipocytes were treated with 200 µM of either trans‐9‐18:1, trans‐11‐18:1, trans‐13‐18:1, cis‐9‐18:1 or BSA vehicle control for 120 h. Trans‐9‐18:1 increased total cell FA content (µmole/well) compared to other FA treatments, which was mainly related to the accumulation of trans‐9‐18:1 in the cells. Adipocytes were able to desaturate a significant proportion of absorbed trans‐11‐18:1 and trans‐13‐18:1 (~20 and 30 % respectively) to cis‐9,trans‐11‐18:2 and cis‐9,trans‐13‐18:2, whereas trans‐9‐18:1 was mostly incorporated intact resulting in a greater lipophilic index (i.e. decreased mean FA fluidity) of adipocytes. Trans‐9‐18:1 up‐regulated (P < 0.05) the expression of lipogenic genes including acetyl‐CoA carboxylase (1.65 fold), FA synthase (1.45 fold), FA elongase‐5 (1.52 fold) and stearoyl‐CoA desaturase‐1 (1.49 fold), compared to the control, whereas trans‐11‐18:1 and trans‐13‐18:1 did not affect the expression of these genes compared to control. Our results suggest that the metabolism and lipogenic properties of trans‐11‐18:1 and trans‐13‐18:1, typically the most abundant trans FA in beef from cattle fed forage‐based diets, are similar and are different from those of trans‐9‐18:1, the predominant trans FA in PHVO.
A Maternal High Fat Diet Has Long‐Lasting Effects on Skeletal Muscle Lipid and PLIN Protein Content in Rat Offspring at Young Adulthood
Authors: MacPherson Rebecca E. K. , Castelli Laura M. , Miotto Paula M. , Frendo‐Cumbo Scott , Milburn Amanda , Roy Brian D. , LeBlanc Paul J. , Ward Wendy E. , Peters Sandra J.
Published: December 2014

A maternal high fat diet (HFD) can have adverse effects on skeletal muscle development. Skeletal muscle PLIN proteins (PLIN2, 3 and 5) are thought to play critical roles in lipid metabolism, however effects of HFD on PLIN and lipases (HSL, ATGL, CGI‐58) in mothers as well as their offspring have yet to be investigated. The primary objective of this study was to determine whether maternal HFD would influence skeletal muscle lipase and PLIN protein content in offspring at weaning (19d) and young adulthood (3mo). Female rats (28d old, n = 9/group) were fed control (CON, AIN93G, 7 % soybean oil) or HFD (AIN93G, 20 % lard) for 10 weeks prior to mating and throughout pregnancy and lactation. All offspring were weaned to CON [n = 18/group, 1 female and 1 male pup per litter were studied at weaning (19d) and 3mo of age]. There was no effect of sex for the main outcomes measured in plantaris, therefore male and female data was combined. Maternal HFD resulted in higher triacylglycerol content in pups at 3mo (p < 0.05), as well as in the dams (p = 0.015). Maternal HFD resulted in higher PLIN5 content in pups at weaning and 3mo (p = 0.05). PLIN2 and PLIN5 content decreased at 3mo versus weaning (p < 0.001). HFD dams had a higher PLIN3 content (p = 0.016). Diet had no effect on ATGL, CGI‐58, or HSL content. In conclusion, exposure to a maternal HFD resulted in higher skeletal muscle lipid and PLIN5 content in plantaris of offspring through to young adulthood.
Natural killer cells
Authors: Mandal Arundhati , Viswanathan Chandra
Published: December 2014

Natural killer (NK) cells constitute our bodies' frontline defense system, guarding against tumors and launching attacks against infections. The activities of NK cells are regulated by the interaction of various receptors expressed on their surfaces with cell surface ligands. While the role of NK cells in controlling tumor activity is relatively clear, the fact that they are also linked to various other disease conditions is now being highlighted. Here, we present an overview of the role of NK cells during normal body state as well as under diseased state.Wediscuss the possible utilization of these powerful cells as immunotherapeutic agents in combating diseases such as asthma, autoimmune diseases, and HIV-AIDS. This review also outlines current challenges in NK cell therapy.
Impact of the introduction of neuraxial labor analgesia on mode of delivery at an urban maternity hospital in China
Authors: Hu Ling‐Qun , Zhang Jin , Wong Cynthia A. , Cao Qinying , Zhang Guohua , Rong Huijuan , Li Xia , McCarthy Robert J.
Published: December 2014

Objective

To evaluate the association between the introduction of neuraxial (epidural) labor analgesia and mode of delivery in a large urban maternity hospital in China.

Methods

A single‐intervention impact study was conducted at Shijiazhuang Obstetrics and Gynecology Hospital in Shijiazhuang. Baseline data collection occurred between August 1 and December 31, 2009, when no analgesic method was routinely employed during labor. An intervention was then implemented, consisting of a neuraxial labor analgesia service. The service was fully operational from September 1, 2010, and data were collected to August 31, 2011. The mode of delivery was compared between the different periods.

Results

Neuraxial analgesia rate was used in none of the 3787 deliveries during the baseline period and 3429 (33.5%) of 10 230 in the implementation period. Cesareans were performed in 1533 (40.5%) deliveries in the baseline period and 3441 (33.6%) in the implementation period (difference −6.8%, 99.8% confidence interval [CI] −9.7% to −3.9%; P < 0.0017). The proportion of vaginal deliveries in which forceps were used was unchanged (difference −0.8%, 99.8% CI −0.7% to 2.2%; P = 0.92).

Conclusion

The introduction of epidural analgesia reduced the frequency of cesarean delivery, which improved obstetric and neonatal outcomes.
Sedimentary Proxy Evidence of a Mid-Holocene Hypsithermal Event in the Location of a Current Warming Hole, North Carolina, USA
Authors: Tanner Benjamin R. , Lane Chad S. , Martin Elizabeth M. , Young Robert , Collins Beverly
Published: December 2014

A wetland deposit from the southern Appalachian mountains of North Carolina, USA, has been radiocarbon dated and shows continuous deposition from the early Holocene to the present. Non-coastal records of Holocene paleoenvironments are rare from the southeastern USA. Increased stable carbon isotope ratios (?13C) of sedimentary organic matter and pollen percentages indicate warm, dry early- to mid-Holocene conditions. This interpretation is also supported byn-alkane biomarker data and bulk sedimentary C/N ratios. These warm, dry conditions coincide with a mid-Holocene hypsithermal, or altithermal, documented elsewhere in North America. Our data indicate that the southeastern USA warmed concurrently with much of the rest of the continent during the mid-Holocene. If the current "warming hole" in the southeastern USA persists, during a time of greenhouse gas-induced warming elsewhere, it will be anomalous both in space and time.
Perceptions of the Utility and Acceptability of an Emergency Child Minding Service for Health Staff
Authors: Lawlor Jenine , Franklin Richard C. , Aitken Peter , Hooke Bethany , Furyk Jeremy , Johnson Andrew
Published: December 2014

Abstract

Objective

Tropical Cyclone Yasi in North Queensland activated the disaster management plans at The Townsville Hospital, including the establishment of an emergency child minding service to facilitate the return of staff to work.

Methods

This report describes the establishment of this service and the results of brief electronic surveys that were distributed in the 2 weeks following the cyclone to gather feedback from staff who had placed their children in the care of the service (consumers), staff who had manned the service (staff), and allied health managers whose staff had manned the service (managers).

Results

Overall, approximately 94 episodes of care were provided by the child minding service. All consumers responded “‘yes’” in answer to the question of whether the emergency child minding service facilitated their return to work in the immediate post-disaster period. The survey also identified that a lack of effective advertising may have prevented further uptake of the child minding service.

Conclusions

The provision of an emergency child minding service facilitated the return to work of health care staff immediately after Tropical Cyclone Yasi. More research is needed to understand the effect disaster type has on the uptake of a child minding service. (Disaster Med Public Health Preparedness.2014;8:485-488)
Educating First Responders to Provide Emergency Services to Individuals with Disabilities
Authors: Wolf-Fordham Susan B. , Twyman Janet S. , Hamad Charles D.
Published: December 2014

Objective

Individuals with disabilities experience more negative outcomes due to natural and manmade disasters and emergencies than do people without disabilities. This vulnerability appears to be due in part to knowledge gaps among public health and safety emergency planning and response personnel (responders). We assessed the effectiveness of an online program to increase emergency responder knowledge about emergency planning and response for individuals with disabilities.

Methods

Researchers developed an online course designed to teach public health, emergency planning and management, and other first response personnel about appropriate, efficient, and equitable emergency planning, response, interaction, and communication with children and adults with disabilities before, during, and after disasters or emergencies. Course features included an ongoing storyline, exercises embedded in the form of real-life scenarios, and game-like features such as points and timed segments.

Results

Evaluation measures indicated significant pre- to post-test gains in learner knowledge and simulated applied skills.

Conclusion

An online program using scenarios and simulations is an effective way to make disability-related training available to a wide variety of emergency responders across geographically disparate areas. (Disaster Med Public Health Preparedness. 2014;8:533-540)
When Winning Is Really Losing: Teaching Awards and Women Political Science Faculty
Authors: Butcher Charity , Kersey Timothy
Published: December 2014

Based on a recent survey of political science professors in the United States, women tend to win teaching awards at higher rates than their male counterparts. This may seem like good news for female faculty, particularly amid continuing reports of gender gaps in publications and citations as well as the “leaky pipeline” phenomenon within promotions. However, a closer look at these findings suggests that in cases in which such awards might be most beneficial to women, they are less likely than their male colleagues to receive such acknowledgments. In fact, women are more likely than men to receive these awards only in institutional contexts in which research output is more important for tenure and promotion than teaching. Thus, the achievement of teaching excellence may have an overall negative impact on the advancement of female faculty by reducing their time and focus available for research.
Major Competition? Exploring Perceptions of International Studies Programs among Political Science Department Chairs
Authors: Knotts H. Gibbs , Schiff Jennifer S.
Published: December 2014

Given the growth of international studies (IS) programs and the reciprocal relationship between political science and IS, this article explores perceptions of IS among political science department chairs. We found that the relationship between political science departments and IS programs is largely positive—that is, a majority of chairs supports the existence of IS at their institution, believes the job prospects for political science and IS majors are about equal, and perceives a low level of financial competition between programs. However, we discovered two points of contention: (1) the perception of lower academic rigor of IS programs, and (2) a high level of competition for majors and the “best students.” Perceptions of IS programs are related to a host of factors, including whether a program is housed within the political science department. Finally, we provide suggestions for improving the relationship between political science and IS.
Uncle Wuffle’s Reflections on Political Science Methodology
Authors: Wuffle A
Published: December 2014

This essay consists of idiosynratic reflections on research methodology based on a long career.
Geometrical implication of ion transporters employing an ellipsoidal hollow structure in pseudo-solid electrolytes
Authors: Kim Youngjin , Park Jong Hyuk , Jung Jihoon , Lee Sang-Soo
Published: December 2014

We demonstrate facilitated ion transport in oligomer electrolytes by introducing TiO2 hollow particles of ellipsoidal and spherical shapes.
Fluorescent probes for “off–on” sensitive and selective detection of mercury ions and l-cysteine based on graphitic carbon nitride nanosheets
Authors: Zhang Hanqiang , Huang Yihong , Hu Shirong , Huang Qitong , Wei Chan , Zhang Wuxiang , Kang Lianping , Huang Zhouyi , Hao Aiyou
Published: December 2014

Schematic diagram of the fluorescent probes for the “off–on” detection of mercury ions and l-cysteine.
Hearing Care for Elders: A Personal Reflection on Participatory Action Learning With Primary Care Providers
Authors: Jenstad Lorienne M. , Donnelly Martha
Published: December 2014

Purpose

This report is a reflective critical narrative of the authors' experience with an interdisciplinary collaboration of primary care providers (PCPs) and hearing health care providers (HHCPs) that followed the principles of participatory action research/learning. The goal for this report is to describe the 1st author's observed barriers to PCPs' willingness to learn about hearing health care and the subsequent facilitators to learning.

Method

A team of PCPs and HHCPs created the “Communication: Hearing Loss in Elders” educational module. The module included (a) prereading developed from a combination of literature reviews and contextual factors and (b) a case study.

Results

The authors present the list of topics included in the module, and they reflect on why and how these topics were deemed important by the team. In particular, 2 topics were identified for motivating PCPs' behavior regarding hearing health care: (a) the overlap in symptoms and possible causation among depression, dementia, and hearing loss and (b) how hearing can affect efficiency of care regarding other health issues.

Conclusions

This personal reflective narrative gives the authors' opinions about what can make for a successful collaboration and presents some hypotheses regarding information that may motivate behavior change with regard to hearing care.
True high‐order VCO‐based ADC
Authors: Babaie‐Fishani A. , Rombouts P.
Published: December 2014

A novel approach to use a voltage‐controlled oscillator (VCO) as the first integrator of a high‐order continuous‐time delta–sigma modulator (CT‐DSM) is presented. In the proposed architecture, the VCO is combined with a digital up–down counter to implement the first integrator of the CT‐DSM. Thus, the first integrator is digital‐friendly and hence can maximally benefit from technological scaling.
Non‐invasive characterisation method of carotid plaque composition using ultrasonic velocity‐change imaging
Authors: Mano K. , Sakai M. , Tanigawa S. , Wada K. , Matsunaka T. , Horinaka H.
Published: December 2014

The instability of vessel plaque is thought to be associated with the size and distribution of the lipid core. Ultrasonic B‐mode imaging (ultrasonic amplitude imaging) can visualise plaques, but it is unable to provide information about their composition. Based on the fact that the temperature dependence of ultrasonic velocity differs considerably between water and fat, the motivation for this reported work was that it was thought that ultrasonic velocity‐change imaging could help characterise biological tissues. This method should be able to detect unstable plaque because it is lipid‐rich. A blood vessel phantom of agar base material having similar ultrasonic properties to human soft tissue was made. A small piece of fat was inserted into the blood vessel phantom. Water (instead of blood) was passed through the model vessel using a tube pump. Ultrasonic velocity‐change images were constructed from echo pulse waveforms obtained before and after warming using an ultrasonic transducer. Lipid‐rich areas in the blood vessel phantom were obvious in the ultrasonic velocity‐change image, but not in ultrasonic B‐mode images. These results indicate that ultrasonic velocity‐change imaging is able to characterise carotid artery plaque.
Covert communication using skewed α‐stable distributions
Authors: Cek M.E.
Published: December 2014

A covert communication system using a random carrier having skewed α‐stable distribution is introduced. The proposed method utilises the random signals with skewed α‐stable distributions exhibiting antipodal characteristics to encode the binary information at the transmitter. The receiver recovers these positive and negative skewed α‐stable distributed random signals by switching at different time instants, where only the receiver has the correct switching order. The third‐order statistic, given as sample skewness, is used to determine the message inside the receiver structure. The main purpose of constructing such a communication system is to improve the security aspect by avoiding the self‐repeating autocorrelation behaviour of the transmitted signal in the time domain. The improvement of security is shown by comparing the fractional lower‐order covariance with the reference study. According to the bit error rate results, the proposed method also shows better performance when the impulsiveness of the random carrier having skewed stable distribution is increased.
Poisson‐distribution‐based approach for salient region detection
Authors: Manke R. , Jalal A.S.
Published: December 2014

Attention is given to the behavioural and cognitive process of selectively concentrating on one object in an image while ignoring the others. Attention‐grabbing parts of the visual field are inspected with great keenness. Owing to the limited capacity of the visual system, the retina cannot process everything that falls on it. Instead, the brain relies on attention to bring salient details into focus and filter out background clutter. Salient region detection deals with finding those regions in an image that gain the viewer's attention most. An approach is proposed for salient region detection using the Poisson distribution. The proposed approach does not require any prior training and has been evaluated on the MSRA dataset. The performance is consistent in terms of recall, precision and execution time.
Impact of temperature on negative capacitance field‐effect transistor
Authors: Jo Jaesung , Shin Changhwan
Published: December 2014

A negative capacitance field‐effect transistor (FET) with sub‐60 mV/decade subthreshold slope (SS) at different temperatures (i.e. 14.8 mV/decade at 300 K, 15.7 mV/decade at 360 K and 24.3 mV/decade at 400 K) is experimentally demonstrated. A detailed account of the fabrication process of a negative capacitor is first introduced, followed by the measurement setup for the negative capacitance FET. The impact of temperature on negative capacitance FETs is investigated: (i) the equation for the internal voltage gain in the FET as a function of temperature is derived using Gibbs free energy and (ii) internal voltage against gate voltage (VInt against VG), internal voltage gain against gate voltage (dVInt/dVG against VG) and drain current against gate voltage (ID against VG) curves at different temperatures are measured. It is confirmed that internal voltage amplification can be achieved using the ferroelectric capacitor. However, the magnitude of the step‐up voltage transformation is reduced, i.e. from 9.5 at 300 K to 2.6 at 400 K. Additionally, the SS is slightly increased (i.e. degrading from 14.8 mV/decade at 300 K to 24.3 mV/decade at 400 K) with increasing temperature; however, all SS values are better than the physical limits of SS as dictated by Boltzmann statistics.
500 V dual gate deep‐oxide trench SOI‐LIGBT with improved short‐circuit immunity
Authors: Zhang Long , Zhu Jing , Sun Weifeng , Yu Hui , Du Yicheng , Gu Yan
Published: December 2014

A 500 V deep‐oxide trench silicon‐on‐insulator (SOI) lateral insulated gate bipolar transistor (LIGBT) with improved short‐circuit capability is proposed. The structure features dual trench gates: one gate (G1) extended to the buried oxide and the other gate (G2) arranged in the deep‐oxide trench in the drift region. In the off‐state, G2 acts as an emitter‐side field plate to shield the lateral electric field from the collector side. In the on‐state, negative voltage is applied to G2, leading to a hole inversion layer close to the deep‐oxide trench. The hole inversion layer reroutes the hole current and provides an additional heat dissipation path. Experimental results show that the proposed structure exhibits high short‐circuit immunity without degradation of the breakdown voltage. The short‐circuit withstand time of the proposed structure is 1.55 times that of the conventional one, when the voltage of G2 is −5 V.
Microprocessor‐conducted noise reduction with switched supercapacitors
Authors: Davis A.K. , Gunasekaran M.K.
Published: December 2014

Microprocessors inject noise into the power distribution network (PDN). The point‐of‐load (PoL) converters are preferred for microprocessor supplies to reduce the total number of supplies. In addition, PoL helps in reducing voltage drop and power loss, and leverages the PDN impedance requirements by sending power at higher voltage and stepping down at the required location. Switched capacitor converters (SCCs) are replacing inductor‐dominated buck converters in PoL applications because of their potential to integrate with microprocessors. A new method to reduce microprocessor‐conducted noise by switched supercapacitors built with a 1:1 SCC is proposed. The high‐frequency microprocessor noise conducted into the PDN is reduced by the capacitors switching at low frequency. An analogue implementation of the individual switches with low noise coupling through parasitic capacitance and with current limiting is shown. An insertion loss of 40–20 dB in the conducted frequency range (150 kHz–30 MHz) is observed in experiments. The idea can be used as a standalone method or can be incorporated into conventional SCCs with modifications as an additional feature.
Designing sequence with low sidelobe levels at specified intervals based on PSD fitting
Authors: Wu Hao , Song Zhiyong , Fan Hongqi , Fu Qiang
Published: December 2014

A new approach for designing a sequence that has very low autocorrelation sidelobe levels at specified intervals is proposed. The synthesised autocorrelation function is defined for denoting the autocorrelation properties, and the design problem is formulated as a power spectral density (PSD) fitting problem. In this way, a simple optimisation objective function is obtained and an iterative optimisation technique is applied. The proposed approach is computationally efficient and can generate a sequence with autocorrelation sidelobes that are practically zero at the required lag intervals.
Design of transparent multilayer film antenna for wireless communication
Authors: Kim Youngsung , Lee Changmin , Hong Seungman , Jung Chang Won , Kim Yongjin
Published: December 2014

A multilayer thin film antenna for mobile devices is proposed. The proposed antenna consists of a (indium–zinc–tin oxide) IZTO/Ag/IZTO multilayer film, which is fabricated on a polyimide substrate (εr = 3.5) and a copper layer. The centre frequency of the antenna is 1260 MHz. The geometry of the antenna is made up of a coupled loop and two branches. The proposed antenna was fabricated using the DC pulse sputter instrument. The measured and simulated results of the antenna are given. The measured peak gain of the proposed antenna is 1.66 dBi. The transparency of the IZTO/Ag/IZTO thin film on the polyimide substrate is 86%. The advantages of the proposed antenna are high transparency, low resistivity and flexibility.
Three‐dimensional imaging with terahertz quantum cascade laser and quantum well photodetector
Authors: Zhou Tao , Tan Zhi Yong , Gu Li , Fu Zhang Long , Yao Zheng Wei , Cao Jun Cheng
Published: December 2014

A three‐dimensional (3D) terahertz (THz) computed tomography system with a THz quantum cascade laser as the source and a quantum well photodetector as the receiver is demonstrated. By utilising the algebraic reconstruction technique for image reconstruction, both the external and internal structures of the cross‐section are revealed. The iterative algorithm not only reduces the projections, but also provides good suppression of the beam hardening effect. Finally, the 3D image is built by stacking the images at different heights.
Multi‐user indoor ultra‐wideband wireless communication using polyphase spreading sequences
Authors: Ambroze Marcel A. , Martin Philippa A. , Tomlinson Martin , Taylor Desmond P.
Published: December 2014

In this study, the authors design a multi‐user ultra‐wideband system for indoor wireless communication. The proposed system is useful in multipath radio reception as the full multipath diversity gain is achieved. The system has multiple transmitters and receivers. They use polyphase spreading waveforms which feature low levels of mutual interference and enable each of the channel impulse responses to be measured free from distortion continuously with each data symbol transmission. A key feature of the proposed system is that transmitted waveforms are used which produce outputs from the receiver cross correlators, which are zero on both sides of the main correlation peak, for each radio path. This zero response lasts for a duration in excess of the expected delay spread of the radio channel enabling full Rake processing of the multipath signal. The effects of the low levels of mutual interference are reduced further by using time and frequency hopping, forward error correction and soft decision decoding.
Efficient vehicular ad‐hoc networks routing based on junctions
Authors: Chuang Po‐Jen , Huang Tzu‐Lun
Published: December 2014

In vehicular ad‐hoc networks, high mobility tends to break established paths and cause bandwidth waste because of path reconstruction. To improve the situation, this study presents a new position‐based protocol. The new protocol uses control packets to collect approaching‐the‐junction information and, based on the information, lets moving vehicles adapt their routing paths dynamically when arriving at a junction. Compared with existing protocols which pre‐store massive routing paths in a vehicle, the protocol can accurately relay packets to the destination by significantly reduced control packets. Transmission efficiency is therefore enhanced. Performance evaluation exhibits that the proposed protocol is suitable for practice in highly topology‐changing vehicle‐to‐vehicle environments because it can accurately select targets for packet relay at less routing and storage cost.
Event‐triggered consensus control for second‐order multi‐agent systems
Authors: Xie Duosi , Xu Shengyuan , Li Ze , Zou Yun
Published: December 2014

In this study, an event‐triggered control strategy is proposed to achieve consensus in a multi‐agent system under a directed topology. The proposed control strategy utilises a piecewise continuous control law and an event‐triggering function for each agent. The control law only updates at discrete event instants computed using an event‐triggering function, which depends on the states of the agents at the current and outdated event instant. This control approach is first applied to a first‐order system and is further extended to a second‐order system. Simulation examples are presented to illustrate the efficiency of the proposed control strategy.
Adaptive flocking of non‐linear multi‐agents systems with uncertain parameters
Authors: Zhang Qing , Li Ping , Yang Zhengquan , Chen Zengqiang
Published: December 2014

Dynamic behaviour of multi‐agents raises many novel problems in control theory and robotics. In particular, the flocking problem for a group of mobile agents with uncertain parameters that can always achieve the desired coordination is a great new challenge problem. In this study, a adaptive flocking of non‐linear multi‐agents systems with uncertain parameters is investigated. Firstly, adaptive controller and an update law are designed for multi‐agents system with uncertain parameters. Second, based on the Lyapunov stability theory, it is proved that velocities of each agent come to be the same asymptotically, the collisions among agents can be avoided, and the uncertain parameters can also be identified. Finally, an illustrative example is given to verify the analytical results.
Multi‐agent model‐based predictive control for large‐scale urban traffic networks using a serial scheme
Authors: Zhou Zhao , De Schutter Bart , Lin Shu , Xi Yugeng
Published: December 2014

Urban traffic networks are large‐scale systems, consisting of many intersections controlled by traffic lights and interacting connected links. For efficiently regulating the traffic flows and mitigating the traffic congestion in cities, a network‐wide control strategy should be implemented. Control of large‐scale traffic networks is often infeasible by only using a single controller, that is, in a centralised way, because of the high dimension, complicated dynamics and uncertainties of the system. In this study, the authors propose a multi‐agent control approach using a congestion‐degree‐based serial scheme. Each agent employs a model‐based predictive control approach and communicates with its neighbours. The congestion‐degree‐based serial scheme helps the agents to reach an agreement on their decisions regarding traffic control actions as soon as possible. A simulation study is carried out on a hypothetical large‐scale urban traffic network based on the presented control strategy. The results illustrate that this approach has a better performance with regard to computation time compared with the centralised control method and a faster convergence speed compared with the classical parallel scheme.
Multi‐agent model of group polarisation with biased assimilation of arguments
Authors: Liu Qipeng , Zhao Jiuhua , Wang Xiaofan
Published: December 2014

This study studies the opinion dynamics with group polarisation. The authors say a process of opinion formation is polarising if the final opinions after group discussion are more divergent than individuals’ initial opinions. To capture this phenomenon, they develop a multi‐agent model of opinion formation in which each agent forms their opinion according to all arguments available to them, and during interacting with other agents, they assimilate the arguments of neighbours in a biased manner which can be represented by a modified Polya's urn process. They find that biased assimilation of arguments can result in group polarisation effectively, especially under the condition when the agents are relatively isolated in the network.
Decentralised dynamic games for large population stochastic multi‐agent systems
Authors: Wang Xuehe , Xiao Nan , Xie Lihua , Frazzoli Emilio , Rus Daniela
Published: December 2014

In this study, the authors consider the large population dynamic games where each agent evolves according to a dynamic equation containing the input average of all agents. The long time average (LTA) cost that each agent aims to minimise is coupled with other agents’ states via a population state average (PSA), which is also known as the mean field term. In order to design decentralised controls, the Nash certainty equivalence is introduced. It is shown that the resulting decentralised mean field control laws lead the system to mean‐consensus asymptotically as time goes to infinity. The stability property of the mass behaviour and the almost sure asymptotic Nash equilibrium property of the optimal controls are also guaranteed, and the case with non‐linear system dynamics is also discussed. In addition, the influence of inaccurate mean field information on individual agent is analysed. Finally, they investigate the socially cooperative formulation where the objective is to minimise the social cost as the sum of all individual LTA costs containing the PSA. In this case, they show that the decentralised mean field social controls are the same as the mean field Nash controls for infinite population systems.
Fault diagnosis based on parameter estimation in closed‐loop systems
Authors: Zhai Shouchao , Wang Wei , Ye Hao
Published: December 2014

In this study, parameter faults in a class of non‐identifiable closed‐loop multiple‐input multiple‐output systems are considered. A new parameter estimation‐based fault diagnosis method is proposed. It is known that in open‐loop systems, the system parameters can be identified directly and the on‐line identification results can be used for fault detection and isolation. However, as the closed‐loop system is non‐identifiable because of the correlation introduced by the controller, unique optimal parameter estimation solution cannot be obtained. To address such an issue, a new method to detect and isolate parameter faults of closed‐loop systems without persistent excitation condition is proposed. A reduced‐order model is firstly constructed, which is the projection of the original model onto the orthogonal direction of the controller. By doing this, the aforementioned correlation can be successfully removed. The parameters of the newly constructed model, called as feature parameters, are then identified. The physical faults are finally detected and isolated based on the on‐line identification results of the feature parameters, the projection direction and the known influence matrix. Simulation results are given to show the effectiveness of the proposed method.
Determinants of driver response to variable message sign information in Athens
Authors: Spyropoulou Ioanna , Antoniou Constantinos
Published: December 2014

Variable message signs – which comprise a type of advanced traveller information systems – can affect driver behaviour, especially considering route choice. Hence, their operation is integrated in traffic management strategies for the mitigation of traffic congestion. This research explores the factors determining driver response to variable message signs (VMSs) in the city of Athens. A stated preference questionnaire survey is undertaken and discrete choice analysis is performed towards this aim. More specifically, a random‐effect ordered probit model is estimated that provides insight on the contributory factors that influence driver propensity to divert, when provided with information on incident occurrence via VMSs. Message characteristics, that is, incident type, impact and suggestion for an alternative route, trip characteristics, such as vehicle type, as well as, driver characteristics, such as driver age and income, have been found to affect driver behaviour. Furthermore, appropriate models are also estimated for subsets of the driving population (considering gender and age) and specific similarities and differences between the population behaviours are identified.
Driver fatigue evaluation model with integration of multi‐indicators based on dynamic Bayesian network
Authors: He Qichang , Li Wei , Fan Xiumin , Fei Zhimin
Published: December 2014

Electroencephalogram (EEG) data are an effective indicator to evaluate driver fatigue, but it is usually disturbed by noise. The frequent head nodding, as well as the time of day and total driving time, also have very close relationship with driver fatigue. All these factors should be taken into account for comprehensive driver fatigue evaluation. 50 drivers are recruited to take part in the fatigue‐oriented experiment on the driving simulator. Based on the EEG samples, the EEG‐based indicator of driver fatigue has been established by artificial neural network. Subsequently, a new algorithm is present to compute the head nodding angle with posture data from the passive tools fixed on the driver's head and trunk, respectively, and then head‐based indicator of driver fatigue is determined. Finally, a new evaluation model of driver fatigue is established with integration of four fatigue‐based indicators with DBN (Dynamic Bayesian Network). The results show that it is more accurate to evaluate the driver fatigue compared with the sole EEG‐based indicator.
Longitudinal driving behaviour on different roadway categories: an instrumented‐vehicle experiment, data collection and case study in China
Authors: Wang Jianqiang , Xiong Chenfeng , Lu Meng , Li Keqiang
Published: December 2014

A significant portion of the observed variability in roadway performance can be due to the difference and innate heterogeneity in drivers’ behaviour. Analytical models, stated preference data collection and studies and laboratory‐based simulator experiments are developed to understand the driver behaviour for years. However, little has been done to fill the important gap between the survey/laboratory observed behaviour and the field observed behaviour. This study investigates drivers’ actual behaviour by conducting real‐world field experiments in Beijing's roadway system. In the experiment platform developed, instrumented vehicles are employed for the advanced data collection and analysis in order to understand the impact of roadway category on drivers’ longitudinal behaviour, that is, car‐following and car‐approaching. These behaviour dimensions are identified in this study and quantified by parameters including relative speed, leading vehicle speed, accelerator release, braking activation, distance headway, time headway and time‐to‐collision. The analysis suggests that the drivers’ behaviour variation heavily depends on roadway characteristics, which supplements further theoretical and survey‐based behavioural research. The research findings provide insight for theoretical advances, evaluating driving assistance systems and roadway‐specific incentive designs for traffic harmonisation, speed reduction, collision warning/avoidance, safety enhancement and energy consumption savings.
Reconfigurable reflectarray antenna using single‐layer radiator controlled by PIN diodes
Authors: Li Yuezhou , Abbosh Amin
Published: December 2014

A new type of pattern‐reconfigurable reflectarray phased by reconfigurable unit cells that are centrally controlled by a laptop is presented. The proposed reflectarray with single‐layer radiators employs a phasing element formed by a fixed‐size circular ring attached by a variable‐length arc phase delay line controlled by positive‐intrinsic‐negative diodes. The biasing network of the diodes is properly designed to minimise the interference between the radiating structure and the biasing circuit. To that end, the biasing circuit is placed on a substrate layer below the ground plane whereas the PIN switching diodes are embedded within radiators. The biasing signal is transmitted to the switching elements at the top layer using vias that penetrate the thin substrate layer, the foam layer and the ground plane. Investigations are carried out to verify the performances of the phasing element using a waveguide simulator. A reflectarray, which includes a C‐band offset fed 8 × 8 elements, is configured to switch its main beam between 20° and 30° from the broadside direction. A biasing control unit is added to the fabricated reflectarray and activated using a laptop. The measured radiation patterns of the proposed reflectarray demonstrate a beam‐switching characteristic from the broadside direction, which confirm the proposed design method.
A 65% efficient envelope tracking radio‐frequency power amplifier for orthogonal frequency division multiplex
Authors: Watkins Gavin Tomas , Mimis Konstantinos
Published: December 2014

A high‐efficiency radio‐frequency (RF) power amplifier (PA) is described for high peak‐to‐average power ratio (PAPR) orthogonal frequency division multiplexed signals. Envelope tracking is used, where the supply voltage of an RF amplifier is modulated in harmony with the envelope of the RF signal. The envelope modulator is a split‐frequency design composed of a switched mode power supply (SMPS) for the low‐frequency content, and a hybrid amplifier for the high‐frequency part. The hybrid amplifier combines digital switching with a linear amplifier in a transformer coupled push‐pull structure. For verification, a 7 dB PAPR 3 MHz bandwidth 3rd generation partnership project long‐term evolution (LTE) signal is used. When amplifying the AC component of the LTE envelope signal, 56.2% efficiency is achieved by the hybrid amplifier at 4.6 W output power into a 10 Ω load. Combined with a 94.4% efficient SMPS, the modulator can produce 23.4 W at 83% efficiency. This is combined with an 80.3% efficient 300 MHz RF PA. Together they achieved 65.6% DC‐to‐RF efficiency at 18.2 W RF output power. The measured PAPR at the amplifier output was 6.5 dB.
Parametric analysis of extended hemispherical dielectric lenses fed by a broadband connected array of leaky‐wave slots
Authors: Yurduseven Ozan , Cavallo Daniele , Neto Andrea , Carluccio Giorgio , Albani Matteo
Published: December 2014

In this study, the authors examine the properties of a broadband array of leaky‐wave slots located in the focal plane of an extended hemispherical dielectric lens, to generate several independent beams for imaging applications. The array performance is investigated over a 4:1 band. Parametric analyses are performed by varying the extension length of the lens and the off‐axis distance of the feed point. The results of these analyses provide useful guidelines for the lens design. A spectral domain approach is used to characterise the field generated by the array, while a numerically efficient physical optics algorithm is employed for the analysis of the lens. Simulations performed with Computer Simulation Technology Microwave Studio are used for the validation of the combined analysis methods.
Dual‐band in‐phase filtering power dividers integrated with stub‐loaded resonators
Authors: Li Qun , Zhang Yonghong , Fan Yong
Published: December 2014

A compact microstrip dual‐band in‐phase filtering power divider is presented in this study. The integrated two stub‐loaded resonators are applied to realise the dual‐band filtering response and compact size. Based on the even–odd‐mode analysis, an analytical model of the proposed power divider structure is presented. To improve the frequency selectivity, a source‐load cross coupling is introduced by placing input and output coupling lines closely. A prototype of the dual‐band in‐phase filtering power divider centred at 3.5 and 5 GHz with 3 dB fractional bandwidth of 7.4 and 4.2% is designed, fabricated and measured. The size of the fabricated power divider is 0.27λg × 0.35 λg. The simulated and measured results are presented and show good agreement.
Modified coupled line trans‐directional coupler with arbitrary power divisions and its application to a 180° hybrid
Authors: Liu Hongmei , Fang Shaojun , Wang Zhongbao
Published: December 2014

A modified trans‐directional (TRD) coupler for designing compact coupled line 180° hybrid with non‐interspersed input/output ports is proposed. The modified TRD coupler which is composed of a coupled line and three different shunt capacitors features the characteristic of arbitrary power division and dc blocking. Design equations for the modified TRD coupler are derived using the ABCD matrix. Based on the modified TRD coupler and combined with the coupled line contra‐directional (CTD) coupler, a novel coupled line 180° hybrid is constructed. It inherits the characteristics of the modified TRD coupler including arbitrary power division and dc blocking. Moreover, the input and output ports of the 180° hybrid are non‐interspersed. In the topology of the proposed 180° hybrid, no bond wires, via holes or multilayer structures are required. The configuration of the 180° hybrid is analysed and the design equations are derived. Using the design equations, the coupling coefficients of the CTD and the modified TRD coupler can be flexibly chosen according to different fabrication conditions. As an example to validate the feature of the proposed 180° hybrids, two prototypes with 3 and 6 dB coupling coefficients are devised. The measured results are in good agreement with the simulated ones.
Energy efficiency of small cell backhaul networks based on Gauss–Markov mobile models
Authors: Ge Xiaohu , Tu Song , Han Tao , Li Qiang , Mao Guoqiang
Published: December 2014

To satisfy the recent growth of mobile data usage, small cells are recommended to deploy into conventional cellular networks. However, the massive backhaul traffic is a troublesome problem for small cell networks, especial in wireless backhaul transmission links. In this study, backhaul traffic models are first presented considering the Gauss–Markov mobile models of mobile stations in small cell networks. Furthermore, an energy efficiency model of small cell backhaul networks with Gauss–Markov mobile models has been proposed. Numerical results indicate that the energy efficiency of small cell backhaul networks can be optimised by trade‐off the number and radius of small cells in cellular networks.
Physics‐based insulated‐gate bipolar transistor model with input capacitance correction
Authors: Yang Xin , Otsuki Masahito , Palmer Patrick R.
Published: December 2014

Insulated‐gate bipolar transistor (IGBT) terminal capacitances play an important role in IGBT switching transients. The terminal capacitance modelling is a difficult task because of their operating‐point‐dependent characteristics. In particular, the input capacitance needs careful treatment if accurate modelling is to be performed. Previously, for the planar gate IGBT, the Miller capacitance's voltage dependency is modelled by considering the depletion region growth pattern. For modern trench gate designs, however, there is no similar dynamic model available. Also, its current dependency needs to be accounted for. This study presents an improved IGBT physics‐based model with input capacitance correction. By comparison of experimental and simulation results, the proposed model works well for different types of IGBTs (including the state‐of‐art trench‐gate field‐stop type) over a wide range of operating conditions and is convenient to implement.