bluuebunny/crossref_metadata_2025 huggingface dataset:
Generation of Hypoid Gears on CNC Hypoid Generator
Authors: Simon Vilmos V.
Published: December 2011

In this study, polynomial functions of orders up to five are applied to induce variations in the cradle radial setting and the velocity ratio in the kinematic scheme of the machine tool for the generation of the pinion tooth surfaces corresponding to reduced transmission error amplitudes of a hypoid gear pair. The new CNC hypoid generators have made it possible to perform this nonlinear correction motions for the cutting of the face-milled hypoid gears. An algorithm is developed for the execution of motions on the CNC hypoid generator for the generation of face-milled hypoid gear tooth surface, based on the machine tool setting variation on the cradle-type hypoid generator induced by the optimal polynomial functions up to fifth-order. By using the corresponding computer program, the motion graphs of the CNC hypoid generator are determined for the generation of hypoid gear tooth surface, based on the optimal variation in the velocity ratio in the kinematic scheme and on the variation in the cradle radial setting on a cradle-type generator. The results presented indicate that the variation of the velocity ratio in the kinematic scheme of the hypoid generator induced by a fifth-order polynomial function resulted in a 62% reduction of the maximum transmission error of the gear pair.
Multi-Objective Ease-Off Optimization of Hypoid Gears for Their Efficiency, Noise, and Durability Performances
Authors: Artoni Alessio , Gabiccini Marco , Guiggiani Massimo , Kahraman Ahmet
Published: December 2011

Microgeometry optimization has become an important phase of gear design that can remarkably enhance gear performance. For spiral bevel and hypoid gears, microgeometry is typically represented by ease-off topography. The optimal ease-off shape can be defined as the outcome of a process where generally conflicting objective functions are simultaneously minimized (or maximized), in the presence of constraints. This matter naturally lends itself to be framed as a multi-objective optimization problem. This paper proposes a general algorithmic framework for ease-off multi-objective optimization, with special attention given to computational efficiency. Its implementation is fully detailed. A simulation model for loaded tooth contact analysis is assumed to be available. The proposed method is demonstrated on a face-hobbed hypoid gear set. Three objectives are defined: maximization of gear mesh mechanical efficiency, minimization of loaded transmission error, minimization of maximum contact pressure. Bound constraints on the design variables are imposed, as well as a nonlinear constraint aimed at keeping the loaded contact pattern inside a predefined allowable contact region. The results show that the proposed method can obtain optimal ease-off topographies that significantly improve the basic design performances. It is also evident that the method is general enough to handle geometry optimization of any gear type.
Role of Conservative Moving Least Squares Methods in Reliability Based Design Optimization: A Mathematical Foundation
Authors: Lee Jongsoo , Yong Song Chang
Published: December 2011

The response surface method (RSM) and the moving least squares method (MLSM) are extensively used due to their computational efficiency in solving reliability based design optimization (RBDO) problems. Since traditional RSM and MLSM are described by second-order polynomials, approximated constraints are sometimes unable to ensure feasibility when highly nonlinear and/or nonconvex constraint functions are approximated in RBDO. We explore the development of a new MLSM based meta-model that ensures the constraint feasibility of an optimal solution in RBDO. A constraint-feasible MLSM (CF-MLSM) is devised to realize feasibility regardless of the multimodality/nonlinearity of the constraint function in all approximation processes as well as the variation of random characteristics in RBDO. The usefulness of the proposed approach is verified by examining a nonlinear function problem and an actively controlled structure problem.
Optimization of Microwave Packaging Structure for Directly Modulated Laser Modules Using Three-Dimensional Electromagnetic Model
Authors: Han Wei , Rensing Marc , O’Brien Peter , Peters Frank H.
Published: December 2011

In this paper, the packaging aspects of directly modulated laser (DML) modules are investigated using detailed electromagnetic (EM) simulations. The packaging influences of the laser module are specified in two parts as RF connector and optoelectronic subsystem. By carefully optimizing the package structure, the simulation results show that the insertion loss of the proposed module is less than 1 dB up to 40 GHz. Then, a DML module is packaged and measured based on the optimized package scheme. A resonance free bandwidth of approximately 20 GHz is obtained with a 3 dB bandwidth of about 15 GHz.
Constructal Design Applied to the Geometric Optimization of Y-shaped Cavities Embedded in a Conducting Medium
Authors: Lorenzini G. , Biserni C. , Isoldi L. A. , dos Santos E. D. , Rocha L. A. O.
Published: December 2011

In this paper, we rely on the Constructal method to optimize the geometry of a Y-shaped cavity embedded into a solid conducting wall. The structure has four degrees of freedom. The objective is to minimize the global thermal resistance between the solid and the cavity. The optimization procedure has demonstrated that for larger solids, a cavity shaped as T led to a minimization of the global thermal resistance, while the opposite effect is observed for tall solids, where the optimal shapes are reached when the bifurcated branches deeply penetrates the solid in the vertical direction, according to the Constructal principle of “optimal distribution of imperfections”. The three times minimized global thermal resistance of the Y-shaped cavity has been correlated by power laws as a function of its corresponding optimal configurations. Finally, the performance of the Y-shaped intrusion proved to be superior to that of other basic geometries: the optimized global thermal resistances of the Y-shaped cavities obtained for H/L = 1.0, 2.0, and 5.0 were, respectively 66.61%, 55.37%, and 19.05% lower than the optimal T-shaped cavities under the same thermal and geometric conditions. Furthermore, in comparison with the “finger cavity” shaped as C, the Y-shaped cavities increased the thermal performance in 109.12%, 84.45%, 59.32%, and 20.10% for H/L = 0.5, 1.0, 2.0, and 5.0, respectively.
Self-Driven Electronic Cooling Based on Thermosyphon Effect of Room Temperature Liquid Metal
Authors: Li Peipei , Liu Jing
Published: December 2011

Thermal management has been a critical issue for the safe running of an electronic device. Driving liquid metal with low melting point to extract heat from the thermal source is highly efficient because of its superior thermophysical properties over conventional coolant such as water or the like. In this paper, utilizing thermosyphon effect to drive room temperature liquid metal for electronic cooling was proposed for the first time with its technical feasibility demonstrated. This may lead to a self supported cooling which just utilizes the waste heat produced by the hot chip to drive the flow of liquid metal. And the device thus fabricated will be the one without any external pump and moving elements inside. A series of conceptual experiments under different operational conditions were performed to evaluate the cooling performance of the new method. Meanwhile, the results were also compared with that of water cooling by ways of thermal infrared graph and temperatures acquired by thermocouples. According to the measurements, it was found that the cooling performance of liquid metal was much stronger than that of water, and this will become even better with the increase of heat load, and height difference between the cooler and heater. A theoretical thermal resistance model was established and convective heat transfer coefficient was calculated to interpret the phenomenon with uncertainty analyzed. With further improvement of the present system and liquid metal coolant, this method is expected to be flexibly useful for heat dissipation of light-emitting diode (LED) street lamp, desk computer and radio remote unit (RRU), where confined space, efficient cooling, low energy consumption, dust-proof and water-proof are critically requested.
Deformation Optimization for Inconel718 Superalloy Sheet Hydroforming Numerically and Experimentally
Authors: Yong-chao Xu , Cong Han , Shijian Yuan
Published: December 2011

For deep cylindrical cups with a large height-diameter ratio, it is difficult to be hydroformed in one stroke. Reverse deep drawing is necessary after deep drawing. Deformation optimization was performed to achieve a large drawing ratio and uniform thickness. An inconel718 superalloy deep cup was investigated numerically and experimentally. For a larger total drawing ratio 3.1, different deformations were analyzed for hydromechanical deep drawing and reverse hydromechanical deep drawing under the condition of different loading paths. Effects of deformations were discussed on the thickness. Typical defects were analyzed for different deformation. Optimal deformation was determined for hydromechanical deep drawing and reverse hydromechanical deep drawing. The results show that a superalloy cup with a total drawing ratio 3.1 could be successfully hydroformed, and the minimum thickness is 0.65 mm.
Improved Sheet Bulk Metal Forming Processes by Local Adjustment of Tribological Properties
Authors: Hetzner H. , Koch J. , Tremmel S. , Wartzack S. , Merklein M.
Published: December 2011

This paper is focused on a combined deep drawing and extrusion process dedicated to the new process class of sheet bulk metal forming (SBMF). Exemplified by the forming of gearings, combined sheet and bulk forming operations are applied to sheet metal in order to form local functional features through an intended and controlled change of the sheet thickness. For investigations on the form filling and the identification of significant influencing factors on the material flow, a FE simulation model has been built. The FE model is validated by the results of manufacturing experiments using DC04 with a thickness of 2.0 mm as blank material. Due to the fact that the workpiece is in extensive contact to the tool surface and that the pressure reaches locally up to 2500 MPa, the tribological conditions are a determining factor of the process. Thus, their influence is discussed in detail in this paper. In the first instance, different frictional zones having a distinct effect on the resulting material flow are identified and their effect on improved form filling is demonstrated. Subsequently, a more comprehensive methodology is developed to define tribological zones of forming tools. For this, a system analysis of the digital mock-up of the forming process is performed. Besides friction, other relevant aspects of forming tool tribology like contact pressure, sliding velocity, and surface magnification are considered. The gathered information is employed to partition the tools into tribological zones. This is done by systematically intersecting and re-merging zones identified for each of the criterion. The so-called load-scanning test allows the investigation of the friction coefficient in dependence of the contact pressure and possible loading limits of tribological pairings. It provides an appropriate tribological model test to evaluate tribological measures like coatings, surface textures and lubricants with respect to their targeted application in particular zones. The obtained results can be employed in the layout of further forming processes to reach the desired process behavior. This can be, for example, an improved form filling, less abrasive wear and adhesive damage or lower forming forces, respectively tool load for an improved durability of the die.
An Optimum Flexible Linkage Design of a Fully Variable Electromechanical Valve Actuation System for Internal Combustion Engines
Authors: Hossein Rokni D. T. , Seethaler Rudolf J. , Milani Abbas S.
Published: December 2011

In this study, the mechanical design of a fully flexible valve actuation system (FFVA) for intake valves of naturally aspirated internal combustion engines is optimized. The original FFVA design used a connecting rod in order to transform the rotating motion of the actuator to translating motion of the valve. In the improved design introduced here, the connecting rod is replaced by a flexible linkage. This step is taken in order to eliminate wear and play in the mechanical connections. A detailed design procedure is presented to optimize the heavy fatigue load on this element. Simulations and experimental tests are carried out in order to validate the system performance. It is shown that valve trajectory and energy consumption of the actuation system obtained by simulations are consistent with those observed experimentally. The present redesigned FFVA system then provides more reliable valve motion than previously shown designs.
A Note on Flow Regimes and Churning Loss Modeling
Authors: Changenet C. , Leprince G. , Ville F. , Velex P.
Published: December 2011

The purpose of this study is to investigate the various fluid flow regimes generated by a pinion running partly immersed in an oil bath and the corresponding churning power losses. In a series of papers, the authors have established several loss formulae whose validity depends on two different flow regimes characterized via a critical Reynolds number. Based on some new measurements for transient operating conditions, it has been found that the separation in two regimes may be not accurate enough for wide-faced gears and high temperatures. An extended formulation is therefore proposed which, apart from viscous forces, introduces the influence of centrifugal effects. The corresponding results agree well with the experimental measurements from a number of gears and operating conditions (speed and temperature). Finally, the link between churning and windage losses is examined and it is concluded that the physical mechanisms are different thus making it difficult to establish a general correlation between the two phenomena. In particular, it is shown that tooth geometry is of secondary importance on churning whereas, the air-lubricant circulation being different for spur and helical gears, it substantially impacts windage.
Atomic layer deposition of titanium phosphate on silica nanoparticles
Authors: Wiedmann Monika K. , Jackson David H. K. , Pagan-Torres Yomaira J. , Cho Eunkyung , Dumesic James A. , Kuech T. F.
Published: December 2011

Titanium phosphate was deposited on silica nanoparticles by atomic layer deposition (ALD). The precursors were titanium tetrachloride (TiCl4), trimethylphosphate ((MeO)3PO), and water. Depositions were done at 150–300 °C employing a variety of pulse sequences which altered the self-limiting deposition process. Using the pulse sequence TiCl4-H2O-(MeO)3PO-H2O, the process was self-limiting at 200 °C, and ≤0.3 at.% Cl was incorporated into the material. With the pulse sequence TiCl4-H2O-(MeO)3PO, the process was not completely self-limiting at 200 °C and slightly more Cl incorporation occurred. Using the pulse sequence TiCl4-(MeO)3PO, the process was not self-limiting at 175 or 250 °C, and Cl incorporation was 0.2–2 at.%. The surface area of the material decreased from 300 m2/g for uncoated silica to 46 m2/g for silica coated with 60ALD cycles.
Evaluating operating conditions for continuous atmospheric atomic layer deposition using a multiple slit gas source head
Authors: Ryan Fitzpatrick P. , Gibbs Zachary M. , George Steven M.
Published: December 2011

Continuous atmospheric atomic layer deposition (ALD) is based on the separation of ALD reactants in space rather than in time. In this study, operating conditions for continuous atmospheric ALD were evaluated using a multiple slit gas source head. A test apparatus was constructed consisting of a gas source head that sits above a substrate that is driven by a programmable stepper motor. The gas source head was composed of a series of rectangular channels that spatially separate the ALD reactants. With Al2O3 ALD as the model system, the trimethylaluminum (TMA) reactant channel was positioned in the center and the H2O reactant channels were located on both sides of the TMA channel. This design allowed for deposition of two Al2O3 ALD cycles during one complete back-and-forth translation of the substrate. The gap spacing between the gas source head and substrate was fixed and controlled using micrometers. A series of experiments was conducted using He as a tag gas to determine operating conditions that prevent reactant cross diffusion. There was a wider range of suitable exhaust pumping speeds at a 30 μm gap spacing than at a 100 μm gap spacing. However, mechanical tolerances were not sufficient to allow back-and-forth translation of the substrate at a gap spacing of 30 μm. For Al2O3 ALD at a 100 μm gap spacing, the best Al2O3 film uniformity was achieved when there was a slight vacuum of ∼−5 Torr beneath the gas source head relative to ambient. A larger vacuum beneath the gas source head occurred if the pumping speed of the exhaust channel was higher relative to the N2 supplied to the gas source head. These conditions produced a smaller footprint of Al2O3 deposition resulting from an influx of N2 from the higher pressure ambient. The gas source head had a higher pressure than ambient if the exhaust pumping speed was too low relative to the N2 supply. Under these conditions, reactant gas leaked out the sides and formed Al2O3 powder around the perimeter of the gas source head resulting from the chemical vapor deposition reaction of TMA with ambient moisture. A response surface model was generated to predict the dependence of the pressure beneath the gas source head relative to ambient on the various operating conditions.
Comparison of wet and dry etching of zinc indium oxide for thin film transistors with an inverted gate structure
Authors: Marrs Michael A. , Vogt Bryan D. , Raupp Gregory B.
Published: December 2011

Not only are amorphous oxide semiconductor thin film transistors (TFTs) extremely sensitive to the processing of the active layer, but subsequent layer processing can also impact the performance. Due to this sensitivity, many surface treatments and passivation techniques for the active layer have been developed, but the influence of the etching of the active layer itself has not been explored extensively. These etch steps are especially critical in the manufacture of flexible microelectronics, for which process conditions are inherently limited by thermal stability of the plastic (<200 °C) and incompatibility of the plastic substrate with highly oxidizing chemical environments. Here, a novel dry etch process is compared to typical wet etch process in the context of flexible zinc indium oxide TFT array fabrication on plastic. The dry etch process provides superior control of the sidewall profile and the etch selectivity. These improvements using a dry etch approach decrease the off current of the TFT by 3 orders of magnitude from 2.65 nA for the wet etch process to 0.71 pA using the dry etch with a concurrent improvement in the device yield to 100% (for 120 transistors) with the dry etch. Additionally, the subthreshold slope improves from 1.9 to 1.0 V/decade, while the saturation mobility (6.5 cm2/V s) is not impacted by the etch process.
Synthetic Partial Waves in Ultracold Atomic Collisions
Authors: Williams R. A. , LeBlanc L. J. , Jiménez-García K. , Beeler M. C. , Perry A. R. , Phillips W. D. , Spielman I. B.
Published: December 2011

Extending the Range

Ultracold atomic gases are attractive for quantum simulations of condensed-matter systems because of their tunability; however, while the strength of interactions can be tuned, their range is effectively zero.

Williams
et al.

(p.
314
, published online 8 December) used a pair of Raman lasers to modify the interaction between two colliding Bose-Einstein condensates to include beyond–
s
-wave (
d
- and
g
-wave) contributions. This technique should enable the simulation of more complicated solid-state systems, including those supporting exotic superfluidity.
Capturing Ultrasmall EMT Zeolite from Template-Free Systems
Authors: Ng Eng-Poh , Chateigner Daniel , Bein Thomas , Valtchev Valentin , Mintova Svetlana
Published: December 2011

Controlling Zeolite Nucleation

Small zeolite crystals are of increasing interest as catalysts and for membrane separations because they allow the high selectivity of their cages to be exploited while minimizing the kinetic limitations caused by diffusion.

Ng
et al.

(p.
70
, published online 8 December) synthesized ultrasmall crystals (6 to 15 nanometers) of the EMT zeolite, which has a low framework density and good catalytic properties for hydrocarbon “cracking” (conversion of a large hydrocarbon to smaller ones). The synthesis of EMT has normally required expensive organic templates that limit its industrial use. Careful control of the synthesis conditions, such as ratios of reactants and short bursts of microwave heating, allowed small EMT crystals to nucleate and avoid formation of zeolites with closely related structures.
Complete Genome Sequence of Bacillus cereus Bacteriophage BCP78
Authors: Lee Ju-Hoon , Shin Hakdong , Son Bokyung , Ryu Sangryeol
Published: December 2011

Bacillus cereus
is generally found in soil habitats, and it contaminates a wide variety of foods, causing food poisoning with symptoms such as vomiting and diarrhea. To develop a novel biocontrol agent to inhibit this pathogen, bacteriophage BCP78 belonging to the
Siphoviridae
family was isolated from a fermented food sample. Here we announce the complete genome sequence of BCP78, which may be useful for understanding its inhibition mechanism against
B. cereus
, and describe major findings from the genome annotation.
Five Genome Sequences of Subspecies B1 Human Adenoviruses Associated with Acute Respiratory Disease
Authors: Dehghan Shoaleh , Liu Elizabeth B. , Seto Jason , Torres Sarah F. , Hudson Nolan R. , Kajon Adriana E. , Metzgar David , Dyer David W. , Chodosh James , Jones Morris S. , Seto Donald
Published: December 2011

Five genomes of human subspecies B1 adenoviruses isolated from cases of acute respiratory disease have been sequenced and archived for reference. These include representatives of two prevalent genomic variants of HAdV-7, i.e., HAdV-7h and HAdV-7d2. The other three are HAdV-3/16, HAdV-16 strain E26, and HAdV-3+7 strain Takeuchi. All are recombinant genomes. Genomics and bioinformatics provide detailed views into the genetic makeup of these pathogens and insight into their molecular evolution. Retrospective characterization of particularly problematic older pathogens such as HAdV-7h (1987) and intriguing isolates such as HAdV-3+7 strain Takeuchi (1958) may provide clues to their phenotypes and serology and may suggest protocols for prevention and treatment.
Reversible cerebral vasoconstriction syndrome in a 35-year-old woman following hysterectomy and bilateral salpingo-oophorectomy
Authors: Moussavi Mohammad , Korya Daniel , Panezai Spozhmy , Peeraully Tasneem , Gizzi Martin , Kirmani Jawad F
Published: December 2011

Introduction

Reversible cerebral vasoconstriction syndromes (RCVS) have been documented to take place after an inciting event or illness. They present with headache, altered mental status and focal neurologic findings. The differential diagnosis includes primary angiitis of the central nervous system (PACNS) but one major clinical difference is that the symptoms of RCVS usually resolve within days or weeks whereas PACNS is often fatal. Females of childbearing age are most commonly affected with RCVS. Cases of reversible vasculopathy have also been reported in menopausal women. The hormonal and physiologic changes that take place during the postpartum period and menopause may not be very different from those that occur after a hysterectomy and oophorectomy.

Methods

A case is presented of a 35-year-old woman who underwent a hysterectomy with bilateral salpingo-oophorectomy and then began experiencing severe headaches, visual changes and hemi-sensory loss. Physical examination, imaging and laboratory findings were descriptive of RCVS, and the patient's rapid recovery was consistent with the usual disease progression of a reversible vasculopathy.

Conclusion

A reversible cerebral vasoconstriction syndrome may occur in some circumstances after a hysterectomy with bilateral salpingo-oophorectomy. The mechanisms involved in the development of this condition are explained by current research concerning effects on the vasculature of sudden drops in estrogens and progesterones. More studies are required to further establish the pathophysiology, diagnosis and treatment of this condition.
Costs and efficiency of integrating HIV/AIDS services with other health services: a systematic review of evidence and experience
Authors: Sweeney Sedona , Obure Carol Dayo , Maier Claudia B , Greener Robert , Dehne Karl , Vassall Anna
Published: December 2011

Objectives

To review the literature on the potential efficiency gains of integrating HIV services with other health services.

Design

Systematic literature review. Search of electronic databases, manual searching and snowball sampling. Studies that presented results on cost, efficiency or cost-effectiveness of integrated HIV services were included, focusing on low- and middle-income countries. Evidence was analysed and synthesised through a narrative approach and the quality of studies assessed.

Results

Of 666 citations retrieved, 46 were included (35 peer reviewed and 11 from grey literature). A range of integrated HIV services were found to be cost-effective compared with ‘do-nothing’ alternatives, including HIV services integrated into sexual and reproductive health services, integrated tuberculosis/HIV services and HIV services integrated into primary healthcare. The cost of integrated HIV counselling and testing is likely to be lower than that of stand-alone counselling and testing provision; however, evidence is limited on the comparative costs of other services, particularly HIV care and treatment. There is also little known about the most efficient model of integration, the efficiency gain from integration beyond the service level and any economic benefit to HIV service users.

Conclusions

In the context of increasing political commitment and previous reviews suggesting a strong public health argument for the integration of HIV services, the authors found the evidence on efficiency broadly supports further efforts to integrate HIV services. However, key evidence gaps remain, and there is an urgent need for further research in this area.
A POWER CONSUMPTION ACTIVITY BASED HETEROGENEOUS SOA FRAMEWORK FOR CONTEXT-AWARE HOME SERVICES
Authors: CHO HYUN SANG , KATO TAKEKAZU , YAMAZAKI TATSUYA , HAHN MINSOO
Published: December 2011

The home network is one of the emerging areas from the last century. However, the growth of the home network market is stationary at present. This paper describes the limitations of the home network system and the requirements for overcoming the current limitations. Also described is a new home network service system known as COWS and its easy installation and scalable operation. COWS consists of power consumption monitor and control devices along with a service server that is a complementary combination of Open Service Gateway initiative (OSGi) and web services. A home network system has a dynamic, heterogeneous, distributed, and scalable topology. Service Oriented Architecture (SOA) has been proposed as a solution that satisfies the requirement of a home network, and OSGi and web services are two successful SOA-based frameworks. An included service server has a flexible architecture that consists of a core and extendable service packages. A power consumption monitor and control function provides useful context information for activity-based context-aware services and optimizes the power consumption. The system can be installed easily into existing and new houses to solve the current barrier of the popularization of home network services.
PREDICTION PHASE IN ASSOCIATIVE CLASSIFICATION MINING
Authors: THABTAH FADI , HADI WAEL , ABDELHAMID NEDA , ISSA AYMAN
Published: December 2011

Associative classification (AC) is an important data mining approach which effectively integrates association rule mining and classification. Prediction of test data is a fundamental step in classification that impacts the outputted system accuracy. In this paper, we present three new prediction methods (Dominant Class Label, Highest Average Confidence per Class, Full Match Rule) and one rule pruning procedure (Partial Matching) in AC. Furthermore, we review current prediction methods in AC.

Experimental results on large English and Arabic text categorisation data collections (Reuters, SPA) using the proposed prediction methods and other popular classification algorithms (SVM, KNN, NB, BCAR, MCAR, C4.5, etc.), have been conducted. The bases of the comparison in the experiments are classification accuracy and the Break-Even-Point (BEP) evaluation measures. The results reveal that our prediction methods are very competitive with reference to BEP if compared with known AC prediction approaches such as those of 2-PS, ARC-BC and BCAR. Moreover, the proposed prediction methods outperform other existing methods in traditional classification approaches such as decision trees, and probabilistic with regards to accuracy. Finally, the results indicate that using the proposed pruning procedure in AC improved the accuracy of the outputted classifier.
USING PROGRAM SLICING TO IMPROVE THE EFFICIENCY AND EFFECTIVENESS OF CLUSTER TEST SELECTION
Authors: CHEN ZHENYU , DUAN YONGWEI , ZHAO ZHIHONG , XU BAOWEN , QIAN JU
Published: December 2011

Cluster test selection is a new successful approach to select a subset of the existing test suite in regression testing. In this paper, program slicing is introduced to improve the efficiency and effectiveness of cluster test selection techniques. A static slice is computed on the modified code. The execution profile of each test case is filtered by the program slice to highlight the parts of software affected by modification, called slice filtering. The slice filtering reduces the data dimensions for cluster analysis, such that the cost of cluster test selection is saved dramatically. The experiment results show that the slice filtering techniques could reduce the cost of cluster test selection significantly and could also improve the effectiveness of cluster test selection modestly. Therefore, cluster test selection by filtering has more potential scalability to deal with large software.
TIES WITHIN FAULT LOCALIZATION RANKINGS: EXPOSING AND ADDRESSING THE PROBLEM
Authors: XU XIAOFENG , DEBROY VIDROHA , ERIC WONG W. , GUO DONGHUI
Published: December 2011

Software fault localization techniques typically rank program components, such as statements or predicates, in descending order of their suspiciousness (likelihood of being faulty). During debugging, programmers may examine these components, starting from the top of the ranking, in order to locate faults. However, the assigned suspiciousness to each component may not always be unique, and thus some of them may be tied for the same position in the ranking. In such a scenario, the total number of components that a programmer needs to examine in order to find the faults may vary considerably. The greater the variability, the harder it is for a programmer to decide which component to examine first, and the harder it is to accurately compute the expected effectiveness of a fault localization technique. In this paper, we first conduct a case study, based on three fault localization techniques across four sets of programs, which reveals that the phenomenon of assigning the same suspiciousness to multiple components is not limited to any technique or program in particular. Thus, to reduce variability and alleviate this problem, four tie-breaking strategies are discussed and evaluated empirically in our second case study. Results indicate that the strategies can not only reduce the number of ties in the rankings, but also maintain the effectiveness of the fault localization techniques. We also propose a new metric for evaluating fault localization techniques called CScore, which takes the notion of ties into account. Finally, an additional slicing-based approach to breaking ties is discussed briefly, which aims to provide further insights into tie-breaking and stimulate further research in the area.
ENTROPIC MEASURES OF NON-CLASSICAL CORRELATIONS
Authors: LANG MATTHIAS D. , CAVES CARLTON M. , SHAJI ANIL
Published: December 2011

A framework for categorizing entropic measures of non-classical correlations in bipartite quantum states is presented. The measures are based on the difference between a quantum entropic quantity and the corresponding classical quantity obtained from measurements on the two systems. Three types of entropic quantities are used, and three different measurement strategies are applied to these quantities. Many of the resulting measures of non-classical correlations have been proposed previously. Properties of the various measures are explored, and results of evaluating the measures for two-qubit quantum states are presented.
QUANTUM LOCKING OF CLASSICAL CORRELATIONS AND QUANTUM DISCORD OF CLASSICAL-QUANTUM STATES
Authors: BOIXO S. , AOLITA L. , CAVALCANTI D. , MODI K. , WINTER A.
Published: December 2011

A locking protocol between two parties is as follows: Alice gives an encrypted classical message to Bob which she does not want Bob to be able to read until she gives him the key. If Alice is using classical resources, and she wants to approach unconditional security, then the key and the message must have comparable sizes. But if Alice prepares a quantum state, the size of the key can be comparatively negligible. This effect is called quantum locking. Entanglement does not play a role in this quantum advantage. We show that, in this scenario, the quantum discord quantifies the advantage of the quantum protocol over the corresponding classical one for any classical-quantum state.
QUANTUM DISCORD AND QUANTUM COMPUTING — AN APPRAISAL
Authors: DATTA ANIMESH , SHAJI ANIL
Published: December 2011

We discuss models of computing that are beyond classical. The primary motivation is to unearth the cause of non-classical advantages in computation. Completeness results from computational complexity theory lead to the identification of very disparate problems, and offer a kaleidoscopic view into the realm of quantum enhancements in computation. Emphasis is placed on the "power of one qubit" model, and the boundary between quantum and classical correlations as delineated by quantum discord. A recent result by Eastin on the role of this boundary in the efficient classical simulation of quantum computation is discussed. Perceived drawbacks in the interpretation of quantum discord as a relevant certificate of quantum enhancements are addressed.
AN OPTIMIZED DYNAMICAL DECOUPLING STRATEGY TO SUPPRESS DECOHERENCE
Authors: CONG SHUANG , CHAN LINPING , LIU JIANXIU
Published: December 2011

In this paper, we first present a brief derivation of the dynamical decoupling condition by means of designing control Hamiltonians, which is used to preserve arbitrary quantum states in the case of interactions with environment. According to different time intervals between the adjacent pulses, two important dynamical decoupling schemes: periodic dynamical decoupling (PDD) and Uhrig dynamical decoupling (UDD) are analyzed. Based on the comparison between PDD and UDD, we propose our optimized dynamical decoupling scheme with different time intervals between adjacent pulses which follow a normal distribution. At last numerical simulations are carried out in a three-level atom in Ξ -configuration, we select the non-diagonal element of density matrix as a reference index to compare the performances of suppressing the decoherence of these three strategies, and the results indicate that dynamical decoupling strategy proposed has better performances than that of PDD and UDD have under some low range of the loss of the quantum coherence.
Influence of CO2 on upper airway muscles and chest wall/diaphragm corticomotor responses assessed by transcranial magnetic stimulation in awake healthy subjects
Authors: Borel Jean-Christian , Melo-Silva Cesar Augusto , Gakwaya Simon , Sériès Frédéric
Published: December 2011

Rationale: functional interaction between upper airway (UA) dilator muscles and the diaphragm is crucial in the maintenance of UA patency. This interaction could be altered by increasing respiratory drive. The aim of our study was to compare the effects of hypercapnic stimulation on diaphragm and genioglossus corticomotor responses to transcranial magnetic stimulation (TMS). Methods: 10 self-reported healthy men (32 ± 9 yr; body mass index = 24 ± 3 kg/m−2) breathed, in random order, room air or 5% and then 7% FiCO2, both balanced with pure O2. Assessments included ventilatory variables, isoflow UA resistance (at 300 ml/s), measurement of lower chest wall/diaphragm (LCW/diaphragm), and genioglossus motor threshold (MT) and motor-evoked potential (MEP) characteristics. TMS twitches were applied during early inspiration and end expiration at stimulation intensity 30% above LCW/diaphragm and genioglossus MT. Results: compared with room air, CO2 inhalation significantly augmented minute ventilation, maximal inspiratory flow, tidal volume, and tidal volume/respiratory time ratio. UA resistance was unchanged with CO2 inhalation. During 7% CO2 breathing, LCW/diaphragm MT decreased by 9.6 ± 10.1% whereas genioglossus MT increased by 7.2 ± 9%. CO2-induced ventilatory stimulation led to elevation of LCW/diaphragm MEP amplitudes during inspiration but not during expiration. LCW/diaphragm MEP latencies remained unaltered both during inspiration and expiration. Genioglossus MEP latencies and amplitudes were unchanged with CO2. Conclusion: in awake, healthy subjects, CO2-induced hyperventilation is associated with heightened LCW/diaphragm corticomotor activation without modulating genioglossus MEP responses. This imbalance may promote UA instability during increased respiratory drive.
The influence of respiratory acid-base changes on muscle performance and excitability of the sarcolemma during strenuous intermittent hand grip exercise
Authors: Hilbert M. , Shushakov V. , Maassen N.
Published: December 2011

Acidification has been reported to provide protective effects on force production in vitro. Thus, in this study, we tested if respiratory acid-base changes influence muscle function and excitability in vivo. Nine subjects performed strenuous, intermittent hand grip exercises (10 cycles of 15 s of work/45 s of rest) under respiratory acidosis by CO2 rebreathing, alkalosis by hyperventilation, or control. The Pco2, pH, K+ concentration ([K+]), and Na+ concentration were measured in venous and arterialized blood. Compound action potentials (M-wave) were elicited to examine the excitability of the sarcolemma. The surface electromyogram (EMG) was recorded to estimate the central drive to the muscle. The lowest venous pH during the exercise period was 7.24 ± 0.03 in controls, 7.31 ± 0.05 with alkalosis, and 7.17 ± 0.04 with acidosis ( P < 0.001). The venous [K+] rose to similar maximum values in all conditions (6.2 ± 0.8 mmol/l). The acidification reduced the decline in contraction speed ( P < 0.001) but decreased the M-wave area to 73.4 ± 19.8% ( P < 0.001) of the initial value. After the first exercise cycle, the M-wave area was smaller with acidosis than with alkalosis, and, after the second cycle, it was smaller with acidosis than with the control condition ( P < 0.001). The duration of the M-wave was not affected. Acidification diminished the reduction in performance, although the M-wave area during exercise was decreased. Respiratory alkalosis stabilized the M-wave area without influencing performance. Thus, we did not find a direct link between performance and alteration of excitability of the sarcolemma due to changes in pH in vivo.
Segmental differences in firing properties and potassium currents inDrosophilalarval motoneurons
Authors: Srinivasan Subhashini , Lance Kimberley , Levine Richard B.
Published: December 2011

Potassium currents play key roles in regulating motoneuron activity, including functional specializations that are important for locomotion. The thoracic and abdominal segments in the Drosophila larval ganglion have repeated arrays of motoneurons that innervate body-wall muscles used for peristaltic movements during crawling. Although abdominal motoneurons and their muscle targets have been studied in detail, owing, in part, to their involvement in locomotion, little is known about the cellular properties of motoneurons in thoracic segments. The goal of this study was to compare firing properties among thoracic motoneurons and the potassium currents that influence them. Whole-cell, patch-clamp recordings performed from motoneurons in two thoracic and one abdominal segment revealed both transient and sustained voltage-activated K+currents, each with Ca++-sensitive and Ca++-insensitive [A-type, voltage-dependent transient K+current (IAv)] components. Segmental differences in the expression of voltage-activated K+currents were observed. In addition, we demonstrate that Shal contributes to IAvcurrents in the motoneurons of the first thoracic segment.
Relationships between spike-free local field potentials and spike timing in human temporal cortex
Authors: Zanos Stavros , Zanos Theodoros P. , Marmarelis Vasilis Z. , Ojemann George A. , Fetz Eberhard E.
Published: December 2011

Intracortical recordings comprise both fast events, action potentials (APs), and slower events, known as local field potentials (LFPs). Although it is believed that LFPs mostly reflect local synaptic activity, it is unclear which of their signal components are most closely related to synaptic potentials and would therefore be causally related to the occurrence of individual APs. This issue is complicated by the significant contribution from AP waveforms, especially at higher LFP frequencies. In recordings of single-cell activity and LFPs from the human temporal cortex, we computed quantitative, nonlinear, causal dynamic models for the prediction of AP timing from LFPs, at millisecond resolution, before and after removing AP contributions to the LFP. In many cases, the timing of a significant number of single APs could be predicted from spike-free LFPs at different frequencies. Not surprisingly, model performance was superior when spikes were not removed. Cells whose activity was predicted by the spike-free LFP models generally fell into one of two groups: in the first group, neuronal spike activity was associated with specific phases of low LFP frequencies, lower spike activity at high LFP frequencies, and a stronger linear component in the spike-LFP model; in the second group, neuronal spike activity was associated with larger amplitude of high LFP frequencies, less frequent phase locking, and a stronger nonlinear model component. Spike timing in the first group was better predicted by the sign and level of the LFP preceding the spike, whereas spike timing in the second group was better predicted by LFP power during a certain time window before the spike.
Short- and long-latency somatosensory neuronal responses reveal selective brain injury and effect of hypothermia in global hypoxic ischemia
Authors: Wu Dan , Xiong Wei , Jia Xiaofeng , Geocadin Romergryko G. , Thakor Nitish V.
Published: December 2011

Evoked potentials recorded from the somatosensory cortex have been shown to be an electrophysiological marker of brain injury in global hypoxic ischemia (HI). The evoked responses in somatosensory neurons carry information pertaining to signal from the ascending pathway in both the subcortical and cortical areas. In this study, origins of the subcortical and cortical signals are explored by decomposing the evoked neuronal activities into short- and long-latency responses (SLR and LLR), respectively. We evaluated the effect of therapeutic hypothermia on SLR and LLR during early recovery from cardiac arrest (CA)-induced HI in a rodent model. Twelve rats were subjected to CA, after which half of them were treated with hypothermia (32–34°C) and the rest were kept at normal temperature (36–37°C). Evoked neuronal activities from the primary somatosensory cortex, including multiunit activity (MUA) and local field potential (LFP), were continuously recorded during injury and early recovery. Results showed that upon initiation of injury, LLR disappeared first, followed by the disappearance of SLR, and after a period of isoelectric silence SLR reappeared prior to LLR. This suggests that cortical activity, which primarily underlies the LLR, may be more vulnerable to ischemic injury than SLR, which relates to subcortical activity. Hypothermia potentiated the SLR but suppressed the LLR by delaying its recovery after CA (hypothermia: 38.83 ± 5.86 min, normothermia: 23.33 ± 1.15 min; P < 0.05) and attenuating its amplitude, suggesting that hypothermia may selectively downregulate cortical activity as an approach to preserve the cerebral cortex. In summary, our study reveals the vulnerability of the somatosensory neural structures to global HI and the differential effects of hypothermia on these structures.
Preparing for the unpredictable: adaptive feedback enhances the response to unexpected communication signals
Authors: Marsat Gary , Maler Leonard
Published: December 2011

To interact with the environment efficiently, the nervous system must generate expectations about redundant sensory signals and detect unexpected ones. Neural circuits can, for example, compare a prediction of the sensory signal that was generated by the nervous system with the incoming sensory input, to generate a response selective to novel stimuli. In the first-order electrosensory neurons of a gymnotiform electric fish, a negative image of low-frequency redundant communication signals is subtracted from the neural response via feedback, allowing unpredictable signals to be extracted. Here we show that the cancelling feedback not only suppresses the predictable signal but also actively enhances the response to the unpredictable communication signal. A transient mismatch between the predictive feedback and incoming sensory input causes both to be positive: the soma is suddenly depolarized by the unpredictable input, whereas the neuron's apical dendrites remain depolarized by the lagging cancelling feedback. The apical dendrites allow the backpropagation of somatic spikes. We show that backpropagation is enhanced when the dendrites are depolarized, causing the unpredictable excitatory input to evoke spike bursts. As a consequence, the feedback driven by a predictable low-frequency signal not only suppresses the response to a redundant stimulus but also induces a bursting response triggered by unpredictable communication signals.