bluuebunny/crossref_metadata_2025_split huggingface dataset:
Closed-loop transcranial alternating current stimulation of slow oscillations
Authors: Wilde Christian , Bruder Ralf , Binder Sonja , Marshall Lisa , Schweikard Achim 
Published: September 2015

Abstract
Transcranial alternating current stimulation (tACS) is an emerging non-invasive tool for modulating brain oscillations. There is evidence that weak oscillatory electrical stimulation during sleep can entrain cortical slow oscillations to improve the memory consolidation in rodents and humans. Using a novel method and a custom built stimulation device, automatic stimulation of slow oscillations in-phase with the endogenous activity in a real-time closed-loop setup is possible. Preliminary data from neuroplasticity experiments show a high detection performance of the proposed method, electrical measurements demonstrate the outstanding quality of the presented stimulation device.
Introducing a frequency-tunable magnetic particle spectrometer
Authors: Behrends André , Graeser Matthias , Buzug Thorsten M. 
Published: September 2015

Abstract
Image quality in the new imaging modality magnetic particle imaging (MPI) heavily relies on the quality of the magnetic nanoparticles in use. Therefore, it is crucial to understand the behaviour of such particles. A common technique to analyze the behaviour of the particles is magnetic particle spectrometry (MPS). However, most spectrometers are limited to measurements at a single or multiple discrete excitation frequencies. This paper introduces a frequency-tunable spectrometer, able to perform measurements in the range of 100 Hz - 24kHz.
Creating 3D gelatin phantoms for experimental evaluation in biomedicine
Authors: Stein Nils , Saathoff Thore , Antoni Sven-Thomas , Schlaefer Alexander 
Published: September 2015

Abstract
We describe and evaluate a setup to create gelatin phantoms by robotic 3D printing. Key aspects are the large workspace, reproducibility and resolution of the created phantoms. Given its soft tissue nature, the gelatin is kept fluid during inside the system and we present parameters for additive printing of homogeneous, solid objects. The results indicate that 3D printing of gelatin can be an alternative for quickly creating larger soft tissue phantoms without the need for casting a mold.
Numerical simulation of low-pulsation gerotor pumps for use in the pharmaceutical industry and in biomedicine
Authors: Klopsch Vincent , Germann Tomas , Seitz Hermann 
Published: September 2015

Abstract
The reduction of the pulsation of flow and pressure as well as the increase of the mean flow of a displacement pump will be a benefit to many technical processes, especially in the pharmaceutical industry and in biomedicine. By reducing the flow pulsation, microreactors could work more efficiently and thin-film coatings or fluids in biomedical applications could be applied with more precision. This article presents a new toolbox to analyse and compare different types of gerotor pump gear profiles. The main objective was the development of a toolbox to analyse the mean flow and the flow ripple of theoretical and reverse engineered gerotor gear sets. For that reason, the presented toolbox does not work with analytic functions, but with numerical methods based on point cloud data. A comparison of four different profile types shows that these profiles perform very differently if they are limited by a given maximal outer root diameter and by the numbers of the teeth of both rotors.
Simulation based investigation of source-detector configurations for non-invasive fetal pulse oximetry
Authors: Böttrich Marcel , Ley Sebastian , Husar Peter 
Published: September 2015

Abstract
Transabdominal fetal pulse oximetry is a method to monitor the oxygen supply of the unborn child non-invasively. Due to the measurement setup, the received signal of the detector is composed of photons coding purely maternal and photons coding mixed fetal-maternal information. To analyze the wellbeing of the fetus, the fetal signal is extracted from the mixed component. In this paper we assess source-detector configurations, such that the mixed fetal-maternal components of the acquired signals are maximized. Monte-Carlo method is used to simulate light propagation and photon distribution in tissue. We use a plane layer and a spherical layer geometry to model the abdomen of a pregnant woman. From the simulations we extracted the fluence at the detector side for several source-detector distances and analyzed the ratio of the mixed fluence component to total fluence. Our simulations showed that the power of the mixed component depends on the source-detector distance as expected. Further we were able to visualize hot spot areas in the spherical layer model where the mixed fluence ratio reaches the highest level. The results are of high importance for sensor design considering signal composition and quality for non-invasive fetal pulse oximetry.
Impact of electrode geometry on force generation during functional electrical stimulation
Authors: Loitz Jan C. , Reinert Aljoscha , Schroeder Dietmar , Krautschneider Wolfgang H. 
Published: September 2015

Abstract
The goal of functional electrical stimulation is to restore lost movements by excitation of motor axons inner-vating the target muscle. For optimal electrode placement and geometry the distribution and spatial orientation of the desired motor axons has to be known. In this study, the response of motor axons with different orientations to electrical stimulation was simulated. Three electrode geometries with the same area were used. The simulated axon activation was compared to experimental force measurements and showed good agreements. It is now assumed that optimal electrode geometry does strongly depend on motor axon orientation, which can vary from one subject to the other. Lack of knowledge about the dominant motor axon orientation makes the use of square, round or multi-pad electrodes favorable.
3D-based visual physical activity assessment of children
Authors: Maile S. , Kobel S. , Munz M. , Engleder T. , Steinacker J. M. , Capanni F. 
Published: September 2015

Abstract
In the last decades, an alarming rise in prevalence of childhood overweight and obesity has been observed which is partly attributed to a lack in physical activity and has started to become a public health concern. Therefore, the necessity for accurate physical activity assessment has become more and more apparent. Physical activity can be assessed objectively using accelerometers or combined devices. The application of such devices is sometimes complex and wearing the device may influence the behaviour of the test person. Therefore, assessment without any worn device would be an advantage.
A RGB-D camera device captures motion of the test person in a specific measurement area. After reducing the data and subtraction of the voxel distance, an activity level can be calculated.
The calculated activity level is similar to acceleration data of common monitoring devices. The calculated activity level is the sum of the person’s activity. Little activity with small movement can be differentiated from intense activity with large movement and high acceleration as well as no activity. The data can be structured in body-activity and limb-activity. Classifying those categories increases the benefit of this assessment compared to common accelerometers.
With the RGB-D based assessment objective, contextual information of different physical activity levels can be provided. Physical activity assessment without a worn device offers advantages such as the lack of manipulation of the device and its positioning, also the person’s compliance is no issue influencing the assessment. The RGB-D based assessment is similar to acceleration data and can be converted into comparable data and units after calibration. For more specific assessments a validation with accelerometers and the calibration of the derived data is necessary.
Impact Investing: A Primer and Review of the Literature
Authors: Clarkin John E. , L. Cangioni Carole 
Published: September 2015

AbstractOnce viewed at opposite ends of a spectrum, financial investment and philanthropy are becoming partners in social enterprise development. Impact investing (II) is one of the most innovative ways to bring the resources of the world’s financial markets to the world’s seemingly intractable problems. Since its emergence from the socially responsible investment field, interest in II has grown substantially among a wide variety of practitioners and service providers throughout the world, although scholarly work in the field is scarce. To stimulate interest in this topic, this paper provides a primer and review of the current knowledge base in II. Our wide search of resources on the topic revealed potential contributions from the legal, financial, social entrepreneurship, and project management literature. We found several themes in our synthesis of the reports, articles and surveys included in our study, and several areas where gaps were evident. In general, practitioners focused on the opportunities of II and its potential, while few studies addressed the challenges associated with its implementation. Because II is not a panacea and is inappropriate for many social enterprises, opportunities exist for studies that rigorously examine the applicability and efficacy of II initiatives. This review of the literature provides scholars with an overview of II and a large number of potential resources to aid in their efforts to advance the knowledge base in the field.
Performance Analysis and Optimization of a Dual Warhead System
Authors: Guo Xiao-Jun , Wen He-Ming 
Published: September 2015

Abstract
In modern warfare earth penetrating weapons are often used to defeat enemy’s hardened and deeply buried targets such as aircraft shelters and bunkers. A dual warhead system (DWS) is one of such weapons composed of a forward shaped charge (FSC) and a following through warhead (FTW). In this paper, an analytical model is first proposed to analyze the penetration of an FTW into concrete targets with pre-drilled holes and a DWS is then optimized in order to achieve its best penetration performance. The effects of various parameters on the performance of a dual warhead system penetrating a concrete target are delineated. It transpires that the present model predictions are in good agreement with available experimental data and that the results obtained may be useful for designing such weapon systems.
Analysis of Thermoviscoplastic Effects on Dynamic Necking of Pure Copper Bars during Impact Tension
Authors: Ma Dongfang , Chen Danian , Shanxing Wu , Wang Huanran , Hou Yanjun , Cai Canyuan , Deng Gaotao 
Published: September 2015

Abstract
In order to make effective measure for the stress, strain and strain rate in the specimen, a tensile split Hopkinson bar (TSHB) was optimized in the first loading duration and the thermoviscoplastic models for a pure copper were determined. The deformation of the pure copper bar during the multi-tensile loading including the necking process in the optimized TSHB testing was recorded by a high speed camera and was used in providing an extensional check of the determined thermoviscoplastic models of the pure copper. The thermoviscoplastic models determined in a certain range of strain were employed in numerically simulating the large deformation of the pure copper bar to adjust the thermoviscoplastic model to describing large strain range. The instability strain of thermoviscoplastic materials in simple tension given by Batra et al was compared with the experimental strain at diffuse necking of the pure copper bar and the computed instability strain based on the load-average strain of the pure copper bar. The local necking of the pure copper bar in the optimized TSHB testing was numerically simulated using the micro-mechanical data given by Ragab and was compared with the recorded necking.
Experimental and Numerical Study on the Dynamic Buckling of Ping-pong Balls under Impact Loading
Authors: Zhang X. W. , Yu T. X. 
Published: September 2015

Abstract
By means of ping-pong balls, the dynamic buckling behaviours of thin-walled spherical shells under impact loading are studied both experimentally and numerically. First, the quasi-static tests were conducted on an MTS tester, in which the ball was compressed onto a PMMA plate. Apart from the force-displacement relationship, the evolution of the contact zone between the ball and the plate was obtained by a digital camera. In the impact tests, ping-pong balls were accelerated by an air-gun and then impinged onto a rigid plate with the velocity ranging 10–45 m/s. The local dynamic buckling processes of the ball were recorded by a high-speed digital camera, from which the impact duration, the maximum contact diameter, as well as the contact diameter at snap-through buckling under different impact velocities were obtained. It is found that with the same size of contact zone, the dynamic energy absorption of the ball is much larger than that in the quasi-static tests. To understand the dynamic effects in the impact process, numerical simulations were performed by using different material properties and different impact velocities. The comparison between the experimental and numerical results show that the kinetic energy absorption of the ball is induced by the strain-rate effect, local vibration of the ball and viscous-elastic effect, respectively.
Strain Rate Effects on the Interaction between an Eccentric Matrix Crack and a Circular Inclusion in Composites under Dynamic Loadings
Authors: Liu Lu-Guang , Ou Zhuo-Cheng , Pi Ai-Guo , Duan Zhuo-Ping , Huang Feng-Lei 
Published: September 2015

Abstract
The interaction between an eccentric matrix crack and a circular inclusion in composites was investigated numerically to explore the strain rate effects on the crack deflection/penetration behavior at the matrix-inclusion interface. It is found, with the increase of strain rate, that there will occur in turn the crack deflection, the double-crack fracture and the crack penetration processes for a certain material. Moreover, both higher relative interfacial strength and smaller eccentric angles can redound to the crack penetration. Additionally, it is demonstrated that the strain rate effect on the composite strength is a local structural response characteristic rather than an intrinsic material property, which sounds in agreement with that proposed by previous authors.
A Microscopic Approach to Strain-rate Effect on the Compressive Strength of Concrete-like Materials
Authors: Lu Yubin 
Published: September 2015

Abstract
The micromechanical damage model proposed in Huang et al. (2002) [Huang C, Subhash G, Stanley JV. A dynamic damage growth model for uniaxial compressive response of rock aggregates. Mech Mater 2002;34:267–277] is modified to predict the dynamic damage evolution of concrete subjected to dynamic axial compression loads under different lateral confinement conditions. It shows that the stress–strain response, the compressive strength and the damage growth rate are strongly influenced by the confining pressure. It is also found that when the strain-rate exceeds 10
4
s
-1
, the compressive strength tends to be greatly depended on strain-rates.
Experiments and Modeling of Failure and Fragmentation of Alumina Cylinders under Uniaxial Compression
Authors: Wang Yong-Gang , Hu Jian-Dong , Zhou Feng-Hua 
Published: September 2015

Abstract
Quasistatic compressive strength of alumina cylinders was measured using specimen of two sizes. The strength of the material was dependent on the specimen size. High speed video photography showed that the failure of the cylindrical specimen started from axial splitting, and after failure the specimen fragmentized into small pieces. A fragmentation model was proposed for estimating the average sizes of the fragments. The calculated fragment sizes agreed reasonably well with the experimental data. By using Ls-Dyna software, the failure of cylindrical specimen containing pre-existing crack-like flaws had been simulated.
Numerical Analysis of Shockwave Propagation in Urban Underpass
Authors: Li Xin , Wang Zhihua , Wu Guiying 
Published: September 2015

Abstract
As an indispensable part of transportation system, urban underpass can alleviate traffic congestion and reduce traffic accidents effectively. In order to acquaint the hydrodynamics of shockwave in underpass and assess the potential damage and risk of bombing accidents, a numerical simulation was established to calculate the blast effects originating from the 13Kg TNT. Based on the location of detonation point, the shape of corridor section and the exit’s cover, peak pressure distributions were predicted. The results indicate that the propagation of shockwave in horizontal direction switches to the inclined top of ground in a near-field due to the ground reflection and the set of exit’s cover increases the risk of explosion to the structure and the users.
Radiation Characteristics of a Reflector Antenna Under Shock Wave Loading
Authors: Liu Yan , Yuan Junming , Dong Lu , Huang Fenglei 
Published: September 2015

Abstract
In this paper, the radiation characteristics of a reflector antenna with surface deformation were numerically simulated. The deformation of the reflector antenna under shock wave loading was simulated by LSDYNA software and the far-field patterns of these deformed reflector antennas were calculated by FEKO software. The structure-deformed reflector antennas obtained by LSDYNA software were used as the initial structure of the reflector antennas for calculating the radiation characteristics. The equations were derived to calculate the far field of the reflector antenna according to the physical optics method. As a consequence, according to the encounter modes of the shock wave and the antenna, the far-field patterns were investigated under three conditions of the shock wave frontal action, rear action and oblique action on the antenna.
A Spherical Cavity Expansion Penetration Model for Concrete Based on Hoek–Brown Strength Criterion
Authors: Xu H. , Wen H. M. 
Published: September 2015

Abstract
A spherical cavity expansion model for concrete is first proposed by using an elastic-brittle-plastic material law with Hoek–Brown strength criterion. The constitutive model can capture the basic features of the mechanical response of concrete materials including the effects of strain-softening and pressure hardening (pressure-dependent shear strength) and all the parameters used in the model can be determined from material tests. The forcing function obtained from the spherical cavity expansion analysis is then employed to construct a penetration model for concrete targets struck by ogival-nosed projectiles. It transpires that the present model predictions are in good agreement with experimental observations in terms of penetration depth and ballistic limits/residual velocities in the case of perforation.
Mechanism of High-velocity Projectile Penetration into Concrete
Authors: Wu Hai-Jun , Wang Yinan , Shan Yu , Huang Feng-Lei , Li Qing-Ming 
Published: September 2015

Abstract
The penetration depth of rigid projectiles is investigated using the modified spherical cavity expansion theory and the Holmquist–Johnson–Cook (HJC) model for the concrete targets, in which the model parameters used in the Mohr–Coulomb Tresca-limit yield criterion are obtained by the triaxial compression tests. By comparing the cavity expansion pressures of the concrete samples with two different types of aggregate, the influence of the aggregate hardness on the penetration processes is discussed. With the analysis of the tractions acted on the projectile nose, the influences of the projectile and target material properties as well as the projectile structure on the transition impact velocity are also discussed. By comparing the theoretical results with the experimental data, two penetration mechanisms are demonstrated for the ogive-nose projectile penetration into concrete with the striking velocities up to 2.0 km/s.
Effects of HMX Particle Size on the Shock Initiation of PBXC03 Explosive
Authors: Wen Li-Jing , Duan Zhuo-Ping , Zhang Lian-Sheng , Zhang Zhen-Yu , Ou Zhuo-Cheng , Huang Feng-Lei 
Published: September 2015

Abstract
A series of shock initiation experiments are performed on the PBXC03 explosives in different formulations to understand the influence of the explosive particle size on the shock initiation, and the in-situ pressure gauge data are obtained which show that shock sensitivity decreases with the explosive particle size under the test condition used in this paper. Moreover, a mesoscopic reaction rate model which is calibrated by the experimental data on a medium formulation PBXC03 explosive is adopted and then applied to predict numerically the shock initiation of other PBXC03 explosives in different formulations. The numerical results are in good agreement with the experimental data.
CFD Predictions of Sufficient Suspension Conditions in Solid-Liquid Agitated Tanks
Authors: Tamburini A. , Brucato A. , Cipollina A. , Micale G. , Ciofalo M. 
Published: September 2015

Abstract
Most research efforts on mechanically agitated solid-liquid contactors have been devoted to the assessment of the minimum impeller speed for complete off-bottom suspension, N

js
. Actually, many industrial vessels are operated at impeller speeds slightly lower than N

js
(Oldshue, 1983; Rieger et al., 1988). This suggests that the sufficient suspension condition, which is quantitatively specified in this paper by introducing a suitably defined quantity N

ss
, may represent a valid alternative to that of complete suspension.
In the present work time-dependent RANS simulations were carried out with the aim of predicting the achievement of sufficient suspension conditions. The Eulerian-Eulerian Multi Fluid Model along with the Sliding Grid algorithm were employed. The Unsuspended Solids Criterion (USC) (Tamburini et al., 2011a) was adopted to distinguish the suspended particles from the unsuspended ones.
The experimental suspension curves (mass fraction of suspended particles versus impeller speed, i.e. x

susp
vs N) collected by Tamburini et al. (2011a) and the relevant N

ss
values were predicted by the present CFD simulations and a very good agreement was found, with maximum discrepancies of about 4%.
Moreover, CFD results were used to test the ability of some N

js
assessment methods proposed in the literature to predict sufficient suspension conditions.
Highly Non-linear Microfluidic Resistor Elements for Flow Rate-dependent Addressing of Microchannels
Authors: Rajah Luke , White Duncan A. , Knowles Tuomas P. J. 
Published: September 2015

Abstract
We have developed a microfluidic resistor element exhibiting a hydrodynamic resistance that is strongly dependent on the pressure at the inlet of the device. Such an element can be used to construct microfluidic circuits that possess a highly non-linear dependence between the pressure and the flow rate, in contrast to conventional microfluidic resistors. We show that this effect can be exploited to create valves which do not require an external control line, but are actuated directly through the pressure difference between the single inlet and outlet of the device. Furthermore, we show that the flux to each branch of the circuit controlled by the valve can be fixed for high or low flow rates by modifying the fixed resistances internal to the device.
Equiatomic cerium intermetallics CeXX′ with twopelements
Authors: Pöttgen Rainer , Chevalier Bernard 
Published: September 2015

AbstractThe equiatomic CeXX′ phases (XandX′ = elements of the 3rd, 4th, or 5thmain group) extend the large series of CeTXintermetallics (T= electron-rich transition metal). These phases crystallize with simple structure types, i.e. ZrNiAl, TiNiSi, CeScSi, α-ThSi2, AlB2, and GdSi2. In contrast to the CeTXintermetallics one observes pronounced solid solutions for the CeXX′ phases. The main influence on the magnetic ground states results from the absence ofdelectrons. All known CeXX′ phases show exclusively trivalent cerium and antiferro- or ferromagnetic ordering at low temperatures. The crystal chemical details and some structure-property relationships are reviewed.