Normal penetration of an eroding projectile into an elastic–plastic target

The main objective of the present work is to describe normal penetration of a deformable projectile into an elastic–plastic target. The force imposed on the projectile by the target is generally a complex function of the strength of the target material, the projectile velocity, its diameter and shape, as well as the instantaneous penetration depth. When this force exceeds a certain critical value the projectile begins to deform. At moderate-to-high values of the impact velocity, the projectile's tip material flows plastically with large deformations causing the formation of a mushroom-like configuration. This process is accompanied by erosion of the projectile material. In the rear (“elastic”) part of the projectile the deformations remain small and the region can be approximated as a rigid body being decelerated by the projectile's yield stress. The general model allows one to predict the penetration depth, the projectile's eroded length and the crater diameter. It has been shown that in the limit of very high impact velocities the present model reduces to the well-known form of the hydrodynamic theory of shaped-charge jets. Also, a simplified asymptotic formula for the crater radius has been derived which includes the effect of the target's yield stress and compares well with experimental data for very high impact velocities.     

To build an energy-saving society

To speed up the development of cycling economy and build an energy-saving society is the key point of work in the coming years for the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China (AQSIQ). AQSIQ has recently worked out a scheme entitled 相似文献   

Coherent coupling between an optomechanical membrane and an interacting photon Bose–Einstein condensate

In this paper, we study theoretically the optomechanical interaction of an interacting condensate of photons with an oscillating mechanical membrane in a microcavity. We show that in the Bogoliubov approximation, due to the large number of photons in the condensate, there is a linear strong effective coupling between the Bogoliubov mode of the photonic Bose–Einstein condensate (BEC) and the mechanical motion of the membrane which depends on the photon–photon scattering potential. This coupling leads to the cooling of the mechanical motion, the normal mode splitting (NMS), the squeezing of the output field and the entanglement between the excited mode of the cavity and the mechanical mode. Since the photon condensation occurs at room temperature, this hybrid system can be potentially considered as a room temperature source of squeezed light as well as a suited candidate for exploring the quantum effects. We show that, on one hand, the non-linearity of the photon gas increases the degree of the squeezing of the output field of the microcavity and the efficiency of the cooling process at high temperatures. On the other hand, it reduces the NMS in the displacement spectrum of the oscillating membrane and the degree of the optomechanical entanglement. In addition, the temperature of the photonic BEC can be used to control the above-mentioned phenomena.     

Monitoring of an ATP-binding aptamer and its conformational changes using an α-hemolysin nanopore

An aptamer is a specific oligonucleotide sequence that spontaneously forms a secondary structure capable of selectively binding an analyte. An aptamer's conformation is the key to specific binding of a target molecule, even in the case of very closely related targets. Nanopores are a sensitive tool for the single-molecule analysis of DNA, peptides, and proteins transporting through the pore. Herein, a single α-hemolysin natural nanopore is utilized to sense the conformational changes of an adenosine 5'-triphosphate (ATP)-binding aptamer (ABA). The known DNA sequence of the ABA is used as a model to develop real-time monitoring of molecular conformational changes that occur by binding targets. The native, folded ABA structure has a nanopore unfolding time of 4.17 ms, compared with 0.29 ms for the ABA:ATP complex. A complementary 14-mer strand, which binds the ABA sequence in the key nucleic acids responsible for folding, forms linear duplex DNA, resulting in a nanopore transit time of 0.50 ms and a higher capture probability than that of the folded ABA oligomer. Competition assays between the ABA:ATP and ABA:reporter complexes are carried out, and the results suggest that the ABA:ATP complex is formed preferentially. The nanopore allows for the detection of an ABA in its folded, ATP-bound, and linear conformations.     

Optische Diagnostik an Vakuumlichtbögen

Advanced optical diagnostics of vacuum arc plasma for switching applications Vacuum technology provides environmentally compatible and emission-free solutions for switching in power grids. A high number of operations under standard load conditions, safe and reproducible short-circuit current interruption capability, and maintenance-free operation are few examples of advantages of vacuum circuit breakers. Further development of such devices requires fundamental knowledge about the switching process and interaction of materials used with the working medium – the vacuum arc plasma. The optical diagnostics offers numerous methods for the characterization of the arc plasma and surrounding components, like e.g. electrodes and chamber walls. Studies of plasma and electrode phenomena by combination of optical and electrical diagnostics allow for material qualification, choice of design and arc extinguishing mechanisms.     

When did a reduced speed limit show an effect? Exploratory identification of an intervention time

In a statistical analysis of accident data before and after a speed limit reduction, the time of the countermeasure is, of course, well known. Our understanding of the accident process may, however, be increased if we assume in a thought experiment that this time is unknown. We ask if the data themselves can tell us something about such a possible time. By means of time series of traffic accidents in Zurich before and after a speed limit reduction, different exploratory methods are presented to identify the "unknown" time of this measure. For most of the investigated series, the most likely time was found to lie in the three months before the true introduction. A possible explanation of this result may be that the media already informed the public before the countermeasure was actually introduced. This finding leads to an improved parsimonious intervention model which distinguishes between a possible "preintervention effect" and the usual "intervention effect."     

Is subsidizing entry an optimal policy?

Public subsidies in support of new firm foundation are amongthe most frequently used instruments of industrial policy inthe Euro zone. This paper analyses their effectiveness and efficiencyvis-à-vis some features of the overall process of industrydynamics in Italian manufacturing. To this end, the survivaland growth patterns of new small firms are investigated usinga unique dataset on electrical and electronic engineering inItaly. As regards survival, our results confirm the findingsof other studies, namely that the hazard rates are particularlyhigh in the early stages of firm's lifecycle. As far as growthis concerned, the main finding in this study is that Gibrat'sLaw fails to hold in the years immediately following start-up,when smaller firms must ‘rush’ in order to achievea size large enough to enhance their likelihood of survival;conversely, in later stages of a firm's lifecycle this Law cannotbe ignored. These results radically question the use of subsidiesas an optimal policy for the support of new entries, since thesubsidy brings about a major bias in the process of market selection(including substitution and deadweight effects) and hampersthe post-entry scale adjustment of newborn firms.     

Intrinsic Localized Modes in an Order-parameter-preserving Antiferromagnet

Intrinsic localized modes in an order-parameter-preserving antiferromagnet are investigated withemploying the Dyson-Maleev transformation and the coherent-state ansatz. These modes which be-low the magnon frequency band correspond to a local large-angle, low-frequency precessional mo-tion of spins, quantum states of which are characterized by the indefiniteness of the number of rele-vant magnons.     

Generalized abelès relations for an anisotropic thin film with an arbitrary dielectric tensor: comments

The Cojocaru generalization of the 2 x 2 extended Jones matrix method, placed in a wider context of previous approaches to anisotropic optical thin films, is analyzed from a complementary perspective. This, contrary to initial belief, allows for a simple proof that one may include multiple reflections by taking into account total fields into the anisotropic film, and this therefore provides support for a more widespread use of the method.     

Asymmetric contacts on a single SnO₂ nanowire device: an investigation using an equivalent circuit model

Electrical contacts between the nanomaterial and metal electrodes are of crucial importance both from fundamental and practical points of view. We have systematically compared the influence of contact properties by dc and EIS (Electrochemical impedance spectroscopy) techniques at various temperatures and environmental atmospheres (N(2) and 1% O(2)). Electrical behaviors are sensitive to the variation of Schottky barriers, while the activation energy (E(a)) depends on the donor states in the nanowire rather than on the Schottky contact. Equivalent circuits in terms of dc and EIS analyses could be modeled by Schottky diodes connected with a series resistance and parallel RC circuits, respectively. These results can facilitate the electrical analysis for evaluating the nanowire electronic devices with Schottky contacts.     

The success-index: an alternative approach to the h-index for evaluating an individual’s research output

Among the most recent bibliometric indicators for normalizing the differences among fields of science in terms of citation behaviour, Kosmulski (J Informetr 5(3):481?C485, 2011) proposed the NSP (number of successful paper) index. According to the authors, NSP deserves much attention for its great simplicity and immediate meaning??equivalent to those of the h-index??while it has the disadvantage of being prone to manipulation and not very efficient in terms of statistical significance. In the first part of the paper, we introduce the success-index, aimed at reducing the NSP-index??s limitations, although requiring more computing effort. Next, we present a detailed analysis of the success-index from the point of view of its operational properties and a comparison with the h-index??s ones. Particularly interesting is the examination of the success-index scale of measurement, which is much richer than the h-index??s. This makes success-index much more versatile for different types of analysis??e.g., (cross-field) comparisons of the scientific output of (1) individual researchers, (2) researchers with different seniority, (3) research institutions of different size, (4) scientific journals, etc.     

Future challenges for MOVPE – an industrial perspective

This paper attempts to predict where the future challenges lie for MOVPE from an industrial perspective. These key challenges include the need to provide ever-increasing capacity and ever-reducing costs, the need to cope with increasing complexity and the tightening of tolerances, the need for device-level qualification, the shortening of product development cycles and the need to address environmental sustainability and recycling issues. The paper identifies two themes that the author believes are crucial to the resolution of these key challenges. The themes are those of modeling and simulation and monitoring and control.     

FMS Scheduling Simulation Based on an Evolution Algorithm

A FMS（flexible manufacturing system) scheduling algorithm based on an evolution algorithm (EA) is developed by intensively analyzing and researching the scheduling method in this paper.Many factors related to FMS scheduling are considered sufficiently.New explanations for a common kind of the encoding model are given.The rationality of encoding model is ensured by designing a set of new encoding methods,while the simulation experiment is performed.The results show that a FMS scheduling optimum problem with multi-constraint conditions can be effectively solved by a FMS scheduling simulation model based on EA.Comparing this method with others,this algorithm has the advantage of good stability and quick convergence.     

Fibre composite bridge decks — an alternative approach

This paper presents initial results of a study into the structural behaviour of a new type of fibre composite bridge deck. The deck, which uses a particulate filled resin core can be produced for costs similar to steel and concrete decks. The manufacturing method is suitable for both small and large-scale production runs and does not require large up front investments. Aspects of the design and method of manufacture are presented together with test results for two different size decks.     

Nickel Oxide as an Electrode Material for Supercapacitors

The preparation of Ni oxide films and their capacitive mechanism are discussed in this paper.Nickel oxide film electrodes perform pseudocapacitance in aqueous KOH and NaOH but perform double layer capacitance in LiClO4/PC(propylence carbonate).The effect of increasing the specific capacitance was observed when Ni oxide film electrodes are doped with Co.A specific capacitance of around 70 F/g was achieved when using Ni oxide films doped with Co as electrodes and 1mol/L aqueous KOH or NaOH as an electrolyte.     

How flat is an air-cleaved mica surface?

Muscovite mica is an important mineral that has become a standard substrate, due to its easy cleavage along the {001} planes, revealing a very flat surface that is compatible with many biological materials. Here we study mica surfaces by dynamic atomic force microscopy (AFM) operated in the non-contact mode (NC-AFM) under ultra-high vacuum (UHV) conditions. Surfaces produced by cleaving in UHV cannot be imaged with NC-AFM due to large surface charges; however, cleavage in air yields much less surface charge and allows for NC-AFM imaging. We present highly resolved NC-AFM images of air-cleaved mica surfaces revealing a rough morphology originating from a high density of nanometre-sized particles. Among these particles, we find regularly shaped structures indicating the growth of crystallites on the surface. The contamination layer cannot be removed by degassing in UHV; even prolonged heating at a temperature of 560?K under UHV conditions does not yield an atomically flat surface.     

Requirements for forming an ‘e-supply chain’

In today's digital economy, web-based integration of the enterprises to form an e-supply chain is a critical weapon for orchestrating the whole supply chain towards competitiveness. This paper intends to discuss the requirements for forming an e-supply chain from different perspectives, such as integration with the legacy systems, timing and prior presence of ERP (enterprise resources planning) systems, BPR (business process re-engineering) needs of internal and external business processes and business intelligence/decision support needs. A look at technical knowledge and structure to construct an e-supply chain is provided. Challenges involved in forming an e-supply chain are also briefly mentioned as a separate section in this paper. During the study, requirements are gathered by making a review of recent literature.