bluuebunny/crossref_metadata_2025 huggingface dataset:
Algorithmic optimisation of histogram intersection kernel support vector machine‐based pedestrian detection using low complexity features
Authors: Bilal Muhammad
Published: February 2017

Histogram intersection kernel support vector machine (SVM) is accepted as a better discriminator than its linear counterpart when used for pedestrian detection in images and video frames. Its computational complexity has, however, limited its use in practical real‐time detectors. To circumvent this problem, prior work proposed a low complexity detection framework based on integer‐only histograms of oriented gradient features which allow a look‐up table‐based implementation of kernel SVM leading to further simplification without compromising detection performance. This work describes several important enhancements made in the original framework related to the pre‐processing steps, feature calculation and training setup. Resultantly, the augmented framework, proposed in this study, stands out in terms of the detection accuracy and computational complexity compared to contemporary detectors. The best detector described in this study achieves 8 and 2% lesser miss rates (MRs) on ETH and INRIA pedestrian datasets, respectively, compared to the well‐known boosting cascades‐based aggregate channel feature detector despite avoiding complex floating point operations. Moreover, the proposed detector performs exceptionally better in scenarios where less than 10−2 false positives per image are desired as demonstrated through the MR versus false positive curves.
Investigation of irreversible demagnetisation in switched flux permanent magnet machines under short‐circuit conditions
Authors: Li Guang‐Jin , Taras Petrica , Zhu Zi‐Qiang , Ojeda Javier , Gabsi Mohamed
Published: February 2017

The irreversible magnet demagnetisation phenomena are investigated, under both healthy and short‐circuit conditions for a switched flux permanent magnet (SFPM) machine. The temperature effects on permanent magnet material are taken into account and the influence of short‐circuit current over demagnetisation is evaluated. To calculate the short‐circuit current (mainly inter‐turn short circuit), the MATLAB/Simulink model has been employed. The aforementioned short‐circuit current is then fed to the finite‐element model, so the demagnetisation analysis can be carried out. Various fault scenarios are investigated, including a high speed and high fault severity. It is found that the short‐circuit current has limited effect on the magnet demagnetisation due to particular features of the SFPM machines. The mechanism of demagnetisation has been revealed and found out to be mainly due to temperature rise and poor PM materials utilisation. Experiments have been carried out to validate the MATLAB/Simulink model for short‐circuit current predictions.
Improved position offset based parameter determination of permanent magnet synchronous machines under different load conditions
Authors: Liu Kan , Feng Jianghua , Guo Shuying , Xiao Lei , Zhu Z.Q.
Published: February 2017

This study proposes a novel method for the parameter determination of permanent magnet (PM) synchronous machines under different load conditions. It can identify the total dq‐axis flux linkages and also the PM flux linkage separately by the addition of a pair of negative and positive position offsets. It is also noteworthy that the influence of uncertain inverter non‐linearity and winding resistance is cancelled during the modelling process, and the experimental results on two different PM synchronous machines show a good agreement with the finite‐element prediction results. More importantly, it shows good performance in online tracking the variation of PM flux linkage, which is an important feature for aiding the condition monitoring of PMs, for example, monitoring the temperature of PMs.
Influence of pole and slot combinations on vibration and noise in external rotor axial flux in‐wheel motors
Authors: Deng Wenzhe , Zuo Shuguang , Lin Fu , Wu Shuanglong
Published: February 2017

This study provides a detailed finding of the influence of pole and slot combinations on vibration and noise in external rotor axial flux in‐wheel motors (AFWMs). Firstly, electromagnetic force exerted on the surface of permanent magnet is discussed and a two‐dimensional fast Fourier transformation is implemented to analyse its spatial distribution and frequency characteristics. Then, a multiphysics model is developed to predict the vibration and noise and figure out the main origin from the perspective of electromagnetism. The influence of pole and slot combinations on vibration and noise is also analysed via the proposed model. Finally, the effect of load on vibration and noise in AFWMs is further investigated. It turns out that zeroth spatial order of axial electromagnetic force is the main origin of vibration and noise in axial flux motors, which is quite different from radial flux motors. Moreover, AFWMs with larger lowest common multiple (LCM) of pole number (2p) and slot number (Qs) show lower noise level and for the motors that satisfy LCM(2p,Qs) ≠ 6p, vibration and noise are greatly influenced by load. This study provides guidance for the design of low noise AFWMs.
PMSG‐based wind energy conversion systems: survey on power converters and controls
Authors: Yaramasu Venkata , Dekka Apparao , Durán Mario J. , Kouro Samir , Wu Bin
Published: February 2017

The permanent magnet synchronous generator (PMSG) is dominantly used in the present wind energy market. Reflecting the latest wind energy market trends and research articles, this study presents a survey on important electrical engineering aspects for PMSG‐based megawatt‐level wind energy conversion systems (WECSs). A comprehensive analysis on power converter topologies for wind turbines (WTs), grid integration of wind farms, digital control schemes, fault‐ride‐through compliance methods, and future trends is presented. The updated market share, technology trends, WT products information, in‐depth technical analysis, and promising research works highlighted in this study will help the reader to understand the state‐of‐the‐art and emerging technologies for PMSG‐based WECS.
Sequence current component and its power direction‐based improved protection for spot network with DERs
Authors: Zhang Zhihua , Crossley Peter , Xu Bingyin , Yin Mingze
Published: February 2017

Spot network has very high supply reliability and it is beneficial for integrating distributed energy resources (DERs). In conventional spot network, all the feeders are the sole power source, providing unidirectional power to the secondary network. The equipped network protector prevents power flow from the network to the feeder, to protect the transformer against upstream fault. If there are amounts of DERs injected, excess power inside the network will lead to frequently mistrip of the protector because the cause of reverse power cannot be differentiated. This study presents an improved protection for spot network with high penetration of DERs. It is based on the sequence current component and its power direction. There are various positive and negative components when different types of fault occur at different locations. Based on the sequence current variation, the reverse power caused by fault or by DERs can be differentiated. Then the fault can be located by comparing the sequence power direction among feeders. Based on this theory, the sectionalized bus‐bar protection is also discussed. The simulation results prove that the proposed method functions effectively on enhancing the penetration amount of DERs and improving the supply reliability further.
Online monitoring of generator damping using dissipation energy flow computed from ambient data
Authors: Chen Lei , Sun Ming , Min Yong , Xu Xialing , Xi Jianghui , Li Yong
Published: February 2017

Online monitoring of generator damping assists in identifying wrong parameters or detrimental changes in generator control systems that may reduce damping ratios of power system oscillation modes. An approach for generator damping estimation using ambient data during normal operation of power systems is proposed. The ambient phasor measurement data at generator terminal is collected and filtered, and then the dissipation energy flow (DEF) into the generator is computed. The rate of change of the DEF represents the rate of transient energy dissipation of the generator and is used to estimate the generator damping. Test results show the validity and possible applications of the approach. A more comprehensive online monitoring system of small‐signal stability can be constructed using the approach together with system mode estimation methods.
Finite‐difference time‐domain implementation of tensor impedance boundary conditions
Authors: Feizi Mina , Nayyeri Vahid , Keshtkar Asghar
Published: February 2017

Tensor impedance surfaces are modelled using a linear relationship between the tangential electric and magnetic fields at the surface, namely tensor impedance boundary condition (TIBC). To implement TIBC in the finite‐difference time‐domain (FDTD) method, a problem arises: TIBC boundary condition requires that the tangential components of the electric and magnetic fields to be co‐located in both spatial and time grids. However, this requirement is not compatible with the classical leapfrog Yee's algorithm. In this study, the authors present an algorithm for FDTD implementation of TIBC. Numerical examples are presented to demonstrate the stability, and the accuracy of the proposed approach. Validation is achieved by comparison with analytic solutions.
Wideband CP slot antenna with backed FSS reflector
Authors: Ding Kang , Gao Cheng , Yu Tongbin , Qu Dexin
Published: February 2017

A wideband, circularly polarised (CP), frequency selective surfaces (FSSs) backed dual‐slot antenna is designed and fabricated. It consists of two crescent‐shaped slots, an L‐shaped feed‐line and an FSS reflector. The single crescent‐shaped slot structure is employed to obtain CP radiation first. Then, it is found that the beam‐tilted problem can be solved by extended dual‐slot design. With the FSS reflector placed under the dual‐slot antenna, unidirectional radiation is achieved and axial ratio bandwidth of the proposed antenna could be improved simultaneously. The measured results offer a 56% (3.5GHz, 4.5–8.0GHz) CP bandwidth, and the 10 dB impedance bandwidth is 84.8% (5.48GHz, 3.72–9.20GHz). By introducing the FSS reflector, 10 dBi of peak gain is also obtained at 5.6GHz which is greatly enhanced when compared with the antenna without FSS. The advantages of the proposed antenna are the simple structure, high gain and broad CP bandwidth.
RKADE‐ADI FDTD applied to analysis of terahertz wave characteristics of plasma
Authors: Wanjun Song , Hou Zhang
Published: February 2017

Terahertz (THz) radar has a good potentiality for the countermeasure of plasma stealth due to its high imaging resolution and strong penetration ability. It is of great importance to investigate the THz wave characteristics of plasma for applying THz radar to counter plasma stealth. The Runge–Kutta ADE alternating direction implicit finite difference time domain (RKADE‐ADI FDTD) for plasma is proposed through combining the RKADE technique with ADI FDTD, which is aimed at acquiring more accurate THz wave characteristics of plasma. The dispersion error and dissipation error of the RKADE technique are analysed and compared with those of ADE scheme. Through comparing the reflection and transmission coefficients of a plasma sheet calculated by the RKADE‐ADI FDTD with those obtained by ADE‐ADI FDTD, error‐optimised ADE‐ADI FDTD, and analytical method, the validity of the proposed method is confirmed. The propagation and reflection characteristics of non‐magnetised plasma sheet at THz band are analysed by the proposed method. The reasons for the phenomena of THz wave interaction with plasma are interpreted theoretically.
High‐performance tight coupling microstrip directional coupler with fragment‐type compensated structure
Authors: Wang Lu , Wang Gang , Sidén Johan
Published: February 2017

In this study, a design scheme for high‐performance tight coupling microstrip coupler is proposed by adding a fragment‐type compensated structure between two loosely coupled lines. Owing to its flexibility and adaptability, the fragment‐type compensated structure can not only provide a quarter‐wavelength phase shift for coupling enhancement, but also compensate the difference in the phase velocities of the even‐ and odd‐modes for high directivity. Design of the fragment‐type compensated structure can be implemented by multi‐objective optimisation searching with several design objectives characterising tight coupling couplers. A high‐efficiency optimisation searching strategy by using two‐dimensional median filtering operator is employed to improve the efficiency of multi‐objective optimisation. For demonstration, a high‐performance 3‐dB tight coupling directional coupler operating at 2GHz is designed. The measurement data demonstrates a maximum directivity of 47dB, above 25dB directivity in a 21.5% bandwidth, a maximum variation of 0.3dB in the coupling level and a maximum power division ratio of 0.6dB, which indicate the overall performance better than the previously reported 3‐dB couplers. In addition, a simplified theoretical analysis of the proposed coupler and full‐wave simulated results are provided for better understanding of the fragment‐type compensated structure.
TD optimal sampling interpolation over a plane from NF data collected through a non‐conventional plane‐rectangular scanning
Authors: D'Agostino Francesco , Ferrara Flaminio , Gennarelli Claudio , Guerriero Rocco , Migliozzi Massimo
Published: February 2017

A time domain (TD) optimal sampling interpolation (OSI) scheme to efficiently reconstruct the transient field radiated by an ultra‐wide band (UWB) antenna over a plane in the near‐field (NF) region from a minimum number of its NF TD samples, acquired through a non‐conventional plane‐rectangular scanning, is developed in this study. Such a result has been achieved by properly exploiting the non‐redundant sampling representations of electromagnetic fields and modelling the antenna by a proper rotational surface. Since the UWB antennas are usually quasi‐planar, such a surface can be conveniently chosen coincident with that of an oblate ellipsoid or with that formed by two bowls with the same circular aperture and possibly different lateral bends. Numerical examples, which assess the accuracy of the related TD OSI representations, are reported.
Performance of underwater optical wireless communication with multi‐pulse pulse‐position modulation receivers and spatial diversity
Authors: Peppas Kostas P. , Boucouvalas Anthony C. , Ghassemloy Zabih
Published: February 2017

In this study, the performance of underwater optical wireless communication systems employing spatial diversity and multi‐pulse position modulation techniques is assessed. The effects of inter‐symbol interference, oceanic turbulence and receiver noise are taken into account. Oceanic turbulence is modelled by the log‐normal distribution which is regarded as an appropriate model for weak turbulence conditions. For the system under consideration, approximate analytical expressions for the average bit error probability are deduced. The impact of the number of transmitting and receiving apertures, the achievable data rate and the water type on system performance is also investigated. Various numerical results are presented that demonstrate the proposed analysis.
Bifurcation analysis and operation region estimation of current‐mode‐controlled SIDO boost converter
Authors: Zhou Shuhan , Zhou Guohua , Wang Yao , Liu Xiaotian , Xu Shungang
Published: February 2017

To analyse the stable operation range with varied input and output voltages, bifurcation behaviours and operation region of current‐mode‐controlled single‐inductor dual‐output (SIDO) boost converter are investigated. The inductor current borders and one‐dimensional discrete‐mapping model are deduced firstly. On the basis of the model, the bifurcation diagram and corresponding Lyapunov exponent spectrum are analysed. Two transition conditions and boundary equations of the converter are derived, where its working state transits from stability to instability, and its operation mode shifts from continuous conduction mode (CCM) to discontinuous conduction mode (DCM). The operation region with different circuit parameters can be estimated and divided through the parameter space maps, which is significant for the design of circuit parameters and stability control. Time‐domain simulations and experimental results are presented to verify the theoretical analysis results. The research results show that the three kinds of bifurcation behaviours including period‐doubling bifurcation, border collision bifurcation, and tangential bifurcation exist in the current‐mode‐controlled SIDO boost converters. Different from the previous works, the SIDO boost converter has a particular bifurcation trend when border collisions occur. The trend includes that operation mode shifts from CCM to DCM and then backs to CCM, and system period increases or decreases doubly.
Interleaved full ZVZCS DC–DC boost converter: analysis, design, reliability evaluations and experimental results
Authors: Tarzamni Hadi , Babaei Ebrahim , Zarrin Gharehkoushan Amirreza , Sabahi Mehran
Published: February 2017

In this study, a new interleaved full soft switching DC–DC boost converter with a high power reliability is proposed. To achieve soft switching, a simple auxiliary circuit consisting of one switch, one diode, one inductor and two capacitors is employed in each single‐phase DC–DC boost converter connected in parallel. All switches and diodes, including main and auxiliary ones, operate under soft switching conditions. These soft switching conditions consist of zero voltage and zero current switching (ZVZCS) for all switches and diodes at switching transitions except the output diodes, which turn off only with zero current switching. The soft switching technique used in this study decreases power losses which leads the converter to have higher efficiency and reliability. Also, the auxiliary circuit is located out of the main power path preventing high voltage and current stresses on the switches. In this study, operational modes analysis, design procedure, power reliability evaluations and laboratory prototype results with switching frequency of 20 kHz, input voltage of 48 V and output power of 40 W are presented.
Synthesis, field emission of various ZnSe nanostructures by hydrothermal methods
Authors: Gao Zhiyong , Xue Shaolin , Yu Qi , Xie Pei , Wang Youya , Feng Hange , Li Lingwei
Published: February 2017

In this work, grass‐like, needle‐like and chrysanthemum‐like ZnSe nanostructures have been prepared by hydrothermal method at 200°C for 24 h successfully. With different amounts of diethanolamine, various morphologies of ZnSe formed. The structures, morphologies and crystal orientation of as‐synthesised ZnSe nanostructures were characterised by X‐ray diffractometer (XRD) and scanning electron microscope. The experiment result of XRD indicated that the structures of all as‐synthesised ZnSe nanomaterials were cubic crystal. The field emission (FE) properties of as‐synthesised samples were tested and the results revealed that the FE properties were influenced by the morphologies significantly. The FE measurement showed that the chrysanthemum‐like ZnSe nanostructures had the best FE properties with a high field enhancement factor of 4328 and a low turn‐on electric field of 3.4 V μm−1 among all the as‐synthesised ZnSe nanostructures. The reaction mechanism of various morphologies ZnSe was also explained as follow.
Photoinduced Reduction of Nitrobenzenes to Primary Aromatic Amines
Authors: Chuang Gary , Huang Hua-Hsuan , Chen Yu-Feng , Niu Guang-Hao
Published: February 2017

Primary aromatic amines were synthesized from the corresponding nitrobenzenes via photoinduced reduction. The reaction was found to be effective when nitrobenzenes with electron-withdrawing substituents were irradiated with a broad band of UV light centered at 306 nm. When reactions are completed, products could be isolated by acid–base extraction or by column chromatography. This presenting photoreaction procedure for the synthesis of primary aromatic amines from the corresponding nitrobenzenes proceeds without the need of a sensitizer in isopropanol or THF. Without the usage of catalysts, or stoichiometric reducing reagent containing heavy metals, this photoinduced reduction of nitrobenzenes fulfils the concept of green chemistry.
The GLM representation of the global relation for the two-component nonlinear Schrödinger equation on the interval
Authors: Xu Jian , Fan Engui
Published: February 2017

In a previous work, we show that the solution of the initial-boundary value problem for the two-component nonlinear Schrödinger equation on the finite interval can be expressed in terms of the solution of a 3×3 Riemann-Hilbert problem. The relevant jump matrices are explicitly given in terms of the three matrix-value spectral functions s(k), S(k), and SL(k), which in turn are defined in terms of the initial values, boundary values at x = 0, and boundary values at x = L, respectively. However, for a well-posed problem, only part of the boundary values can be prescribed, the remaining boundary data cannot be independently specified but are determined by the so-called global relation. Here, we use a Gelfand-Levitan-Marchenko representation to derive an expression for the generalized Dirichlet-to-Neumann map to characterize the unknown boundary values in physical domain, which is different from the approach, in fact it analyzed the global relation in spectral domain, used in the previous work. And, we can show that these two representations are equivalent.
Study of the ion kinetic effects in ICF run-away burn using a quasi-1D hybrid model
Authors: Huang C.-K. , Molvig K. , Albright B. J. , Dodd E. S. , Vold E. L. , Kagan G. , Hoffman N. M.
Published: February 2017

The loss of fuel ions in the Gamow peak and other kinetic effects related to the α particles during ignition, run-away burn, and disassembly stages of an inertial confinement fusion D-T capsule are investigated with a quasi-1D hybrid volume ignition model that includes kinetic ions, fluid electrons, Planckian radiation photons, and a metallic pusher. The fuel ion loss due to the Knudsen effect at the fuel-pusher interface is accounted for by a local-loss model by Molvig et al. [Phys. Rev. Lett. 109, 095001 (2012)] with an albedo model for ions returning from the pusher wall. The tail refilling and relaxation of the fuel ion distribution are captured with a nonlinear Fokker-Planck solver. Alpha heating of the fuel ions is modeled kinetically while simple models for finite alpha range and electron heating are used. This dynamical model is benchmarked with a 3 T hydrodynamic burn model employing similar assumptions. For an energetic pusher (∼40 kJ) that compresses the fuel to an areal density of ∼1.07g/cm2 at ignition, the simulation shows that the Knudsen effect can substantially limit ion temperature rise in runaway burn. While the final yield decreases modestly from kinetic effects of the α particles, large reduction of the fuel reactivity during ignition and runaway burn may require a higher Knudsen loss rate compared to the rise time of the temperatures above ∼25 keV when the broad D-T Gamow peak merges into the bulk Maxwellian distribution.
Equation of state and shock compression of warm dense sodium—A first-principles study
Authors: Zhang Shuai , Driver Kevin P. , Soubiran François , Militzer Burkhard
Published: February 2017

As one of the simple alkali metals, sodium has been of fundamental interest for shock physics experiments, but knowledge of its equation of state (EOS) in hot, dense regimes is not well known. By combining path integral Monte Carlo (PIMC) results for partially ionized states [B. Militzer and K. P. Driver, Phys. Rev. Lett. 115, 176403 (2015)] at high temperatures and density functional theory molecular dynamics (DFT-MD) results at lower temperatures, we have constructed a coherent equation of state for sodium over a wide density-temperature range of 1.93-11.60 g/cm3 and 103–1.29×108 K. We find that a localized, Hartree-Fock nodal structure in PIMC yields pressures and internal energies that are consistent with DFT-MD at intermediate temperatures of 2×106 K. Since PIMC and DFT-MD provide a first-principles treatment of electron shell and excitation effects, we are able to identify two compression maxima in the shock Hugoniot curve corresponding to K-shell and L-shell ionization. Our Hugoniot curves provide a benchmark for widely used EOS models: SESAME, LEOS, and Purgatorio. Due to the low ambient density, sodium has an unusually high first compression maximum along the shock Hugoniot curve. At beyond 107 K, we show that the radiation effect leads to very high compression along the Hugoniot curve, surpassing relativistic corrections, and observe an increasing deviation of the shock and particle velocities from a linear relation. We also compute the temperature-density dependence of thermal and pressure ionization processes.
Spin and recombination dynamics of excitons and free electrons in p-type GaAs: Effect of carrier density
Authors: Cadiz F. , Lagarde D. , Renucci P. , Paget D. , Amand T. , Carrère H. , Rowe A. C. H. , Arscott S.
Published: February 2017

Carrier and spin recombination are investigated in p-type GaAs of acceptor concentration NA = 1.5 × 1017 cm−3 using time-resolved photoluminescence spectroscopy at 15 K. At low photocarrier concentration, acceptors are mostly neutral and photoelectrons can either recombine with holes bound to acceptors (e-A0 line) or form excitons which are mostly trapped on neutral acceptors forming the (A0X) complex. It is found that the spin relaxation is faster for free electrons that recombine through the e-A0 transition due to exchange scattering with either trapped or free holes, whereas spin flip processes are less likely to occur once the electron forms with a free hole an exciton bound to a neutral acceptor. An increase in the photocarrier concentration induces a cross-over to a regime where the bimolecular band-to-band (b-b) emission becomes more favorable due to screening of the electron-hole Coulomb interaction and ionization of excitonic complexes and free excitons. Then, the formation of excitons is no longer possible, the carrier recombination lifetime increases and the spin lifetime is found to decrease dramatically with a concentration due to fast spin relaxation with free photoholes. In this high density regime, both the electrons that recombine through the e-A0 transition and through the b-b transition have the same spin relaxation time.
Ballistic one-dimensional transport in InAs nanowires monolithically integrated on silicon
Authors: Gooth J. , Schaller V. , Wirths S. , Schmid H. , Borg M. , Bologna N. , Karg S. , Riel H.
Published: February 2017

We present the monolithic integration and electrical characterization of InAs nanowires (NWs) with the well-defined geometries and positions on Si as a platform for quantum transport studies. Hereby, one-dimensional (1D) ballistic transport with step-like 1D conductance quantization in units of 2e2/h is demonstrated for NWs with the widths between 28 nm and 58 nm and a height of 40 nm. The electric field control of up to four individual modes is achieved. Furthermore, the sub-band structure of the nanowires is investigated using bias spectroscopy. The splitting between the first and the second sub-band increases as the width of the NWs is reduced, whereas the degeneracy of the second sub-band can be tuned by the symmetry of the NW cross section, in accordance with a “particle in a box” model. The length-dependent studies reveal ballistic transport for up to 300 nm and quasi-ballistic transport with a mean free path of 470 nm for longer InAs NW channels at 30 K. We anticipate that the ballistic 1D transport in monolithically integrated InAs NWs presented here will form the basis for sophisticated quantum wire devices for the future integrated circuits with additional functionalities.
Transient thermal analysis of semiconductor diode lasers under pulsed operation
Authors: Veerabathran G. K. , Sprengel S. , Karl S. , Andrejew A. , Schmeiduch H. , Amann M.-C.
Published: February 2017

Self-heating in semiconductor lasers is often assumed negligible during pulsed operation, provided the pulses are ‘short’. However, there is no consensus on the upper limit of pulse width for a given device to avoid-self heating. In this paper, we present an experimental and theoretical analysis of the effect of pulse width on laser characteristics. First, a measurement method is introduced to study thermal transients of edge-emitting lasers during pulsed operation. This method can also be applied to lasers that do not operate in continuous-wave mode. Secondly, an analytical thermal model is presented which is used to fit the experimental data to extract important parameters for thermal analysis. Although commercial numerical tools are available for such transient analyses, this model is more suitable for parameter extraction due to its analytical nature. Thirdly, to validate this approach, it was used to study a GaSb-based inter-band laser and an InP-based quantum cascade laser (QCL). The maximum pulse-width for less than 5% error in the measured threshold currents was determined to be 200 and 25 ns for the GaSb-based laser and QCL, respectively.
Milk production and composition of dairy cows grazing two perennial ryegrass cultivars allocated in the morning and afternoon
Authors: Chen A. , Bryant R. H. , Edwards G. R.
Published: February 2017

The objective of the study was to evaluate the effect of perennial ryegrass cultivar and timing of herbage allocation on herbage nutritive value and milk production of mid-lactation dairy cows. An autumn grazing trial using 48 Friesian × Jersey spring-calving cows was conducted over 10 days. Twelve groups of four cows were allocated to three replicates of four treatments, namely, two perennial ryegrass cultivars (AberMagic or Prospect) offered either after milking in the morning (0830 hours) or afternoon (1630 hours). Cows were offered a daily herbage allowance of 30 kg DM/cow above ground level. There were no significant differences in sward structure and morphological characteristics between cultivars, except for Prospect having a lower average tiller mass (43.1 mg) than AberMagic (48.4 mg). The concentration of water-soluble carbohydrates (WSC) and organic matter digestibility in DM (DOMD) was greater in AberMagic (180 g/kg, 74.2%) than in Prospect (153 g/kg, 71.4%). Herbage DM percentage, WSC concentration and DOMD were lower in the morning than in the afternoon (18.8% vs 22.3% DM; 154 vs 179 g/kg WSC; 72.1% vs 73.5% DOMD). Herbage DM intake (12.0 kg/cow.day), milk yield (17.2 kg/cow.day) and milksolids yield (1.60 kg/cow.day) did not differ significantly among treatments. Cultivar choice and timing of allocation influenced herbage WSC concentration and digestibility, but did not alter milksolids production.
Current and potential system performance on commercial automatic milking farms
Authors: Lyons N. A. , Kerrisk K. L.
Published: February 2017

Dairy farmers considering installing automatic milking systems (AMS) would benefit from adequate contextual information on commercial AMS farm performance. The aim of the present study was to capture key performance indicators related to AMS utilisation on commercial Australian AMS farms on a monthly basis, with the aim of understanding the current and potential system performance. Eight Australian AMS farms were monitored on a monthly basis for a 12-month period. The average number of milking events (milkings/robot.h) was calculated for every hour of the day, on a monthly basis for each of the participating farms. Data exported electronically also allowed the calculation of the number of current and potential extra (both average and maximum) milkings (milkings/robot.day), cows (cows/robot), yield (kg milk/robot.day) and milking time (h/robot.day) for every month on each farm. Despite a wide range in farm performance, the actual milkings (120 milkings/robot.day), cows (51 cows/robot), yield (1263 kg milk/robot.day) and milking time (13.63 h/robot.day) indicated that there is an opportunity to improve these parameters by a maximum of ~60%. To achieve this would require the adoption of a variety of strategies that might be quite farm specific and would be reliant on optimisation of data relating to cow traffic and system utilisation that are relevant to automatic milking systems.
Effects of high concentrations of crude glycerin in diets for feedlot lambs: feeding behaviour, growth performance, carcass and non-carcass traits
Authors: Almeida Marco Tulio Costa , Ezequiel Jane Maria Bertocco , Paschoaloto Josimari Regina , Perez Henrique Leal , Barbosa de Carvalho Vanessa , Filho Edivilson Silva Castro , Branco van Cleef Eric Haydt Castello
Published: February 2017

The effects of high concentrations of crude glycerin were investigated in diets for feedlot lambs. Forty crossbred (Santa Ines × Dorper) uncastrated male lambs (21.7 ± 2.7 kg bodyweight) were assigned to a complete randomised block and subjected to four experimental diets containing 0, 100, 200, or 300 g crude glycerin/kg DM. Animals were weighed at 14-day intervals and were harvested when they reached ~35 kg bodyweight. The feed intake, feeding behaviour, growth performance, carcass and meat traits, and edible non-carcass components were evaluated. The inclusion of more than 100 g/kg crude glycerin in the diets increased days on feed and decreased DM intake and average daily gain. Crude glycerin increased number of chews and the time spent chewing per feed bolus. There were no effects of crude glycerin on pH and colour of Longissimus muscle at 45 min or 24 h after slaughter, as well as on other carcass and edible non-carcass characteristics. The addition of crude glycerin reduced perirenal fat without detrimental effect on others fat deposition sites. In conclusion, the addition of up to 100 g/kg DM in diets for crossbred finishing lambs seems to be the most interesting strategy, as it promotes greatest animal performance. However, the inclusion of up to 300 g/kg DM of the by-product could be possible depending on glycerin market price and the structure of feedlot operation, with favourable economic results despite high inclusions reflect in greater number of days on feed.
Quantifying above and belowground biomass carbon inputs for sugar-cane production in Brazil
Authors: Silva-Olaya A. M. , Davies C. A. , Cerri C. E. P. , Allen D. J. , Mello F. F. C. , Cerri C. C.
Published: February 2017

Expansion of sugarcane crop due to the increasing demand for sugar and ethanol can affect both existing soil carbon (C) stocks, and subsequent input of new C from above and belowground biomass, influencing the overall C intensity and C payback times due to the change of land use. We present above and belowground dry biomass production, shoot-to-root ratio (S:R) as well as the net annual C inputs to the soil for sugarcane in different ratoon stages. The selected areas were as follows: (1) recently planted sugarcane area (PC), (2) first year ratoon cane (RC1) and (3) 4-year ratoon cane (RC4), which were established under Typic Quartzipsamments located in north-eastern São Paulo State. The sugarcane S:R ratios ranged from 6.6 in PC to 3.4 in RC4, and total sugarcane C inputs from 29.6 to 30.8 Mg C ha–1. The overall C balance for land use change requires effects on soil C and also C inputs from previous and future land uses. The sugarcane C input was between 3.7 and 4.0 Mg C ha–1 for each sugarcane cycle of 5 years. When accounting for soil C stock changes and aboveground biomass C losses from the prior land use, the payback times for sugarcane biofuel C debts are reduced by 3, 2 and 1 years for Cerrado wooded, Cerrado grassland and pasture conversions into sugarcane respectively.
Synthesis of carbon nanotubes on the surface of the field cathode of X-ray tube
Authors: Taubin M L , Urusov A A , Bratsuk A V
Published: February 2017

Carbon nanotubes are unique materials being actively investigated in the development of X-ray tubes with a field cathode. The so-called cold-ray tubes. Our contribution in this direction is the use of single crystals W for the anodes and cathodes as substrates. Here are the structures we obtained carbon nanotubes with the catalysts and directly on the surface of tungsten. The report presents results of studies of carbon nanotubes (CNT) formation on metal substrates W and Ni. X-ray microprobe analysis revealed the presence of 8 at. % carbon. Average density of the powder was measured as 5.1 ± 0.1 g/cm3. Calculations have shown that this value corresponds to the density of the carbon content of 8 at. %.
Identification of genetic outliers due to sub-structure and cryptic relationships
Authors: Schlauch Daniel , Fier Heide , Lange Christoph
Published: February 2017

Motivation

In order to minimize the effects of genetic confounding on the analysis of high-throughput genetic association studies, e.g. (whole-genome) sequencing (WGS) studies, genome-wide association studies (GWAS), etc., we propose a general framework to assess and to test formally for genetic heterogeneity among study subjects. As the approach fully utilizes the recent ancestor information captured by rare variants, it is especially powerful in WGS studies. Even for relatively moderate sample sizes, the proposed testing framework is able to identify study subjects that are genetically too similar, e.g. cryptic relationships, or that are genetically too different, e.g. population substructure. The approach is computationally fast, enabling the application to whole-genome sequencing data, and straightforward to implement.

Results

Simulation studies illustrate the overall performance of our approach. In an application to the 1000 Genomes Project, we outline an analysis/cleaning pipeline that utilizes our approach to formally assess whether study subjects are related and whether population substructure is present. In the analysis of the 1000 Genomes Project data, our approach revealed subjects that are most likely related, but had previously passed standard qc-filters.

Availability and Implementation

An implementation of our method, Similarity Test for Estimating Genetic Outliers (STEGO), is available in the R package stego from Github at https://github.com/dschlauch/stego.

Supplementary information

Supplementary data are available at Bioinformatics online.
Volume-Staged Stereotactic Radiosurgery for Intracranial Arteriovenous Malformations: Outcomes Based on an 18-Year Experience
Authors: Pollock Bruce E. , Link Michael J. , Stafford Scott L. , Lanzino Giuseppe , Garces Yolanda I. , Foote Robert L.
Published: February 2017

BACKGROUND: Radiation-based treatment options of large intracranial arteriovenous malformations (AVM) must balance the likelihood of obliteration with the risk of adverse radiation effects (ARE).

OBJECTIVE: To analyze the efficacy and risks of volume-staged stereotactic radiosurgery (VS-SRS) for AVM.

METHODS: Retrospective study of 34 AVM patients having VS-SRS between 1997 and 2012. A median of 2 stages (range, 2-4) was used to treat a median AVM volume of 22.2 cm3 (range, 7.4-56.7). The median AVM margin dose was 16 Gy (range, 14-18); the median radiosurgery-based AVM score was 2.81 (range, 1.54-6.45). The median follow-up after VS-SRS was 8.2 years (range, 3-13.3).

RESULTS: Nidus obliteration was noted in 18 patients (53%) after VS-SRS. The rate of obliteration was 14% at 3 years, 54% at 5 years, and 75% at 7 years. Six patients (18%) had 11 bleeds after VS-SRS. Two patients (6%) remained neurologically stable, 2 (6%) patients had significant deficits, and 2 patients (6%) died. The actuarial risk of a first bleed after VS-SRS was 6% at 1 year, 12% at 3 years, and 19% at 7 years. Six patients (18%) underwent repeat SRS; all achieved nidus obliteration for an overall cure rate of 71%. Two patients (6%) had a permanent ARE after VS-SRS or repeat SRS.

CONCLUSION: VS-SRS permitted large volume intracranial AVM to be treated with a low rate of ARE. Further study is needed on dose escalation and decreasing the treatment volume per stage to determine if this will increase the rate of obliteration with this technique.
Cluster Analysis of Historical and Modern Hard Red Spring Wheat Cultivars Based on Parentage and HPLC Analysis of Gluten‐Forming Proteins
Authors: Malalgoda Maneka , Ohm Jae‐Bom , Meinhardt Steven , Chao Shiaoman , Simsek Senay
Published: February 2017

Thirty hard red spring (HRS) wheat cultivars released between 1910 and 2013 were analyzed to determine how they cluster in terms of parentage and HPLC analysis of gliadins and unreduced proteins. Markers for reduced height genes were assessed to determine associations between semidwarfism and protein composition, as well as quality characteristics. In terms of parentage, the clusters formed were grouped according to release year and semidwarfism. Farinograph development time and stability showed significant (P ≤ 0.05) differences between clusters, indicating improvement of mixing characteristics over time. Flour ash content was significantly different (P ≤ 0.05) between clusters, indicating improved milling quality. The clusters based on the gliadin reverse‐phase HPLC peak binary data did not group cultivars according to release year and the semidwarf characteristic. However, cultivars were grouped according to year in the absorbance area based dendrogram. The clusters based on absorbance area of size‐exclusion HPLC showed significant (P ≤ 0.05) differences for release year, the semidwarf characteristic, and farinograph stability. Overall, the results indicate that the introduction of reduced height genes accompanied the improvements of dough mixing and breadmaking quality characteristics, without altering the composition of gliadin proteins over the last 100 years of HRS wheat breeding.
Replacing noble metals with alternative materials in plasmonics and metamaterials: how good an idea?
Authors: Khurgin Jacob B.
Published: February 2017

Noble metals that currently dominate the fields of plasmonics and metamaterials suffer from large ohmic losses. Some of the new plasmonic materials, such as doped oxides and nitrides, have smaller material loss, and using them in place of metals carries the promise of reduced-loss plasmonic and metamaterial structures, with sharper resonances and higher field concentrations. This promise is put to a rigorous analytical test in this work, which reveals that having low material loss is not sufficient to have reduced modal loss in plasmonic structures. To reduce the modal loss, it is absolutely necessary for the plasma frequency to be significantly higher than the operational frequency. Using examples of nanoparticle plasmons and gap plasmons one comes to the conclusion that, even in the mid-infrared spectrum, metals continue to hold an advantage over alternative media when it comes to propagation distances and field enhancements. Of course, the new materials still have an application niche where high absorption loss is beneficial, e.g. in medicine and thermal photovoltaics.

This article is part of the themed issue ‘New horizons for nanophotonics’.
The impact factor fallacy
Authors: Paulus Frieder Michel , Cruz Nicole , Krach Sören
Published: February 2017

The use of the journal impact factor (JIF) as a measure for the quality of individual manuscripts and the merits of scientists has faced significant criticism in recent years. We add to the current criticism in arguing that such an application of the JIF in policy and decision making in academia is based on false beliefs and unwarranted inferences. To approach the problem, we use principles of deductive and inductive reasoning to illustrate the fallacies that are inherent to using journal based metrics for evaluating the work of scientists. In doing so, we elaborate that if we judge scientific quality based on the JIF or other journal based metrics we are either guided by invalid or weak arguments or in fact consider our uncertainty about the quality of the work and not the quality itself.
Are oceanic fronts ecotones? Seasonal changes along the Subtropical Front show fronts as bacterioplankton transition zones but not diversity hotspots
Authors: Morales Sergio E. , Meyer Moana , Currie Kim , Baltar Federico
Published: February 2017

Ecotones are regarded as diversity hotspots in terrestrial systems, but it is unknown if this “ecotone effect” occurs in the marine environment. Oceanic fronts are widespread mesoscale features, present in the boundary between different water masses, and are arguably the best potential examples of ecotones in the ocean. Here we performed the first seasonal study along an oceanic front, combining 16S rRNA gene sequencing coupled with a high spatial resolution analysis of the physical properties of the water masses. Using the Subtropical Frontal Zone off New Zealand we demonstrate that fronts delimit shifts in bacterioplankton community composition between water masses, but that the strength of this effect is seasonally dependent. While creating a transition zone where physicochemical parameters and bacterioplankton communities get mixed, this ecotone does not result in increased diversity. Thus unlike terrestrial ecotones, oceanic ecotones like fronts are boundaries but not hotspot of bacterioplankton diversity in the ocean.
Real-time decoding of bladder pressure from pelvic nerve activity
Authors: Lubba Carl , Mitrani Elie , Hokanson Jim , Grill Warren M. , Schultz Simon R.
Published: February 2017

Real time algorithms for decoding physiological signals from peripheral nerve recordings form an important component of closed loop bioelectronic medicine (electroceutical) systems. As a feasibility demonstration, we considered the problem of decoding bladder pressure from pelvic nerve electroneurograms. We extracted power spectral density of the nerve signal across a band optimised for Shannon Mutual Information, followed by linearization via piece-wise linear regression, and finally decoded signal reconstruction through optimal linear filtering. We demonstrate robust and effective reconstruction of bladder pressure, both prior to and following pharmacological manipulation.
Effective connectivity inferred from fMRI transition dynamics during movie viewing points to a balanced reconfiguration of cortical interactions
Authors: Gilson Matthieu , Deco Gustavo , Friston Karl , Hagmann Patric , Mantini Dante , Betti Viviana , Romani Gian Luca , Corbetta Maurizio
Published: February 2017

Our behavior entails a flexible and context-sensitive interplay between brain areas to integrate information according to goal-directed requirements. How-ever, the neural mechanisms governing the entrainment of functionally specialized brain areas remain poorly understood. In particular, the question arises whether observed changes in the regional activity for different cognitive conditions are explained by modifications of the inputs to the brain or its connectivity? We observe that transitions of fMRI activity between areas convey information about the tasks performed by 19 subjects, watching a movie versus a black screen (rest). We use a model-based framework that explains this spatiotemporal functional connectivity pattern by the local variability for 66 cortical regions and the network effective connectivity between them. We find that, among the estimated model parameters, movie viewing affects to a larger extent the local activity, which we interpret as extrinsic changes related to the increased stimulus load. However, detailed changes in the effective connectivity preserve a balance in the propagating activity and select specific pathways such that high-level brain regions integrate visual and auditory information, in particular boosting the communication between the two brain hemispheres. These findings speak to a dynamic coordination underlying the functional integration in the brain.