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China has been developed into one of the most active regions in terms of both fundamental and applied research on magnesium (Mg) and its alloys in the world from a solid base laid by its prominent metallurgist and materials scientists over the past decades. Nowadays, a large number of young-generation researchers have been inspired by their predecessors and become the key participants in the fields of Mg alloys, which consequently led to the establishment of China Youth Scholar Society for Magnesium Alloys Research in 2015. Since then, the first two China Youth Scholars Symposiums on Mg Alloys Research had been held at Harbin (2015) and Chongqing (2016) China, respectively. A number of crucial research interests related to fundamental and applied Mg research were discussed at the conferences and summarized in this short perspective, aiming to boost far-reaching initiatives for development of new Mg-based materials to satisfy the requirements for a broad range of industrial employments. Herein, four main aspects are included as follows: i) Plastic deformation mechanism and strengthening strategy, ii) Design and development of new Mg-based materials, iii) Key service properties, and iv) New processing technologies. [ABSTRACT FROM AUTHOR]

This study aimed to (i) estimate additive (a), dominance (d), aa, ad, and ddgenetic variances and effects; (ii) investigate the differences for five genetic variances or effects among crosses between a maize (Zea maysL.) line from the Suwan‐1 heterotic group and five inbred lines from other groups; and (iii) develop a theory to explain the results from Hayman's model and low‐, mid‐, and high‐parent heterosis. Hayman's model was used to evaluate the genetic effects in five six‐generation sets between the Suwan‐1 cross with five lines from other groups. The magnitude of variance was consistent among all crosses for grain yield (GY) and ear length (EL) but different for ear diameter (ED), row number per ear (RE), kernel number per row (KR), and 100‐kernel weight (KW). The a, d, aa, ad, and ddeffects were similar for EL among crosses between lines from different groups, indicating that the effects for EL could be used to differentiate Reid and non‐Reid heterotic groups. We postulated a ‘linked coexpressed genes’ (LCG) model to (i) explain why a, d, aa, ad, and ddvariances and effects might be different when a common line is crossed with other lines and (ii) serve as an improved model explaining heterosis. The LCG model explains what dominance–overdominance theories can explain and explains what dominance–overdominance models do not. For example, it can explain why an inbred line cannot perform like a hybrid and why an F2population for a quantitative trait has a normal distribution.

A unique method for preparation of multi-walled carbon nanotube (MWCNT)- reinforced copper composite is reported. It involves solution phase systhesis MWCNT-implanted cuprous oxide composite spheres, formation of MWCNT/ copper composite spheres after reduction in H2 atmosphere and preparation of the MWCNT/copper bulk with vacuum hot pressing. Scanning Eelectron Microscope image (SEM) of the fracture surfaces indicate MWCNTs are homogeneously dispersed in the composite and bonded to the matrix. In addition, the thermal expansion of the composites at various MWCNTs (0wt%, 1wt%, 5wt%) were investigated. The coefficient of the thermal expansion (CTE) was decreased with increase of the MWCNT content, which are all much lower than that of pure copper.

For the successful realization of product configuration design (PCD) in the condition of mass customization mode, the module encoding methods are studied. By analyzing the product structure model and the process of computer-aided PCD, all related information which is required for the module is decided. This paper proposes a scientific module encoding method suitable for PCD. It describes the geometric features of the modules, the interface relationships and the affiliations between modules. Further more, it introduces additional attribute codes used to evaluate product configuration. By this way the product information can be fully expressed in order to improve the efficiency of PCD.

There is a magnetic field inside thrust bearing. The magnetic field distribution is one of the key factors which decide the running state and performance. With the finite element of ANSYS software, the magnetic field of thrust bearing has been analyzed. The rule of changes between the magnetic field and the influencing factors has been discovered. The analysis shows that the direction of exciting current should be opposite other than identical. The greater the ratio of gap length between stator and rotor and working gap length is, the less magnetic field leakage is. The flux leakage of thrust bearing attains 37 percent when the ratio of the gap is 4.0. If the design of a complete machine is not proper, the flux leakage may attain 20 percent upwards through other gaps although that of the bearing itself is almost zero. Calculation of bearing capacity indicates that theoretical value is not exact due to its neglect of magnetic saturation and flux leakage, while FEM value comparably matches the real substance with considering the magnetic saturation and flux leakage. The research provides the theoretical basis for optimization of system structure and selection of current direction control.

In this paper, based on analyzing the properties of medical Ti-6Al-4V Titanium alloy, the author takes the purpose of studying the machinability of the medical Ti-6Al-4V Titanium alloy and aims at improving the tool durability. The study starts from the tool material, geometrical parameters of the tools, usage for the cutting and other aspects in order to achieve the suitability of selecting cutting tool as well as the optimization of choosing cutting usage which lays the foundation for further investigation of the machinability of the medical Ti-6Al-4V Titanium alloy and carry out the online optimization of cutting parameters.

A new packet CDMA network protocol that employs power-controlled transmissions is proposed and analysed. Three types of codes are used, namely base codes as pilot signals, mobile codes for communication purposes, and common codes for registration or location updating. The performance of such a network is analysed for both fading and non-fading channels.

Needle-like nanocrystalline VO2·H2O, crystallized in a new metastable phase with orthorhombic symmetry (a=6.015, b=4.642, and c=3.763 Å), was synthesized by a long hydrothermal reaction from NH4VO3and hydrazine. The structure and composition of these nanocrystallites were characterized by X-ray powder diffraction, transmission electron microscopy, selected area electron diffraction, infrared absorbency spectroscopy, and thermogravimetric analysis. The influence of chemical reaction conditions on the features of the final products was investigated, and the optimum conditions were found to be 170°C for 15 days with a N2H4concentration of 8.0%. Differential scanning calorimetry was conducted to study the phase transformation from as-prepared metastable VO2·H2O to the more stable (B)VO2and rutile-type VO2.

NaxWO3and KxWO3gels have been prepared by reduction of WO3in aqueous solution with NaBH4or KBH4induced by re-addition of hydrochloric acid. These tungsten bronze gels, as good precursors, were annealed at 600 or 850°C to yield crystalline product. Their compositions are Na0.56WO3and K0.58WO3, respectively, as determined by energy dispersive analysis. X-ray diffraction patterns indicate that NaxWO3annealed at 600°C is a metastable tetragonal phase, which transforms to cubic perovskite phase when annealed at 850°C; while KxWO3annealed at either 600 or 850°C has a tetragonal structure. Resistivity measurement indicates that Na0.56WO3shows a change from metallic to anomalous semiconducting behavior accompanied by phase transformation from tetragonal to cubic phase. This is in contrast to metallic behavior in cubic NaxWO3(x>0.25) generally reported before. Both of the samples of K0.58WO3annealed at 600 and 850°C are semiconducting.

AbstractRaman spectra have been measured on BaxC60binary systems for x=3, 4 and 6. The pentagonal pinch Ag(2) mode exhibits a softening in an approximately proportional manner to the formal valence of C60molecule. This result suggests that the valence of C60in Ba doped systems are understood by the naive ionic crystal model based on Ba2+. The broader Raman peaks in superconducting Ba4C60indicates that the electron-phonon interaction is considerably large comparing to those for Ba3C60and Ba6C60.

The array of aligned, isolated carbon nanotubes was achieved by using chemical vapor deposition catalyzed by round alloy particles on the Ag film. The round alloy particles were prepared by annealing FeNi islands on the Ag film deposited by magnetic sputtering on the silica substrate. The size of the round particles was controlled by the size of the FeNi islands films and the heat treated temperature. The array of carbon nanotubes on the Ag film was obtained at 700°C when the round alloy particles was about 30–80 nm in diameter.

Electron nanodiffraction patterns and high-resolution images from bundles of single-walled carbon nanotubes (SWNTs) have been obtained to determine the helicity and the packing of tubes. It is found that there is no predominating helicity, only a weak tendency of being of `armchair' structure; the inter-tube spacing is close to 0.34 nm and several packing orientations may coexist in a single bundle. Electron energy loss spectra from the bundles of SWNTs and multi-walled carbon nanotubes are used to study electronic structure. The π-bonding is proposed as inter-tube bonding in the bundles. The plasmon energy Epdepends on the diameter and inter-tube (or inter-walled) spacing.

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A partially chlorinated Si(111)-(7 × 7) surface was subjected to 193 nm excimer laser radiation. Scanning tunnelling microscopy (STM) was used to count the number of photoetched atoms per unit of illumination time. The adatom etch rate increased linearly with fluence for peak surface temperatures ranging from room temperature up to 1055°C. The slope of this plot implied a constant etch rate of 3.4 × 10−8atoms per photon, i.e. σe= 1.8 × 10−22cm2. The surface temperature did not influence the etch rate over this broad temperature range. It follows that the removal of Si adatoms was directly due to photolysis, the presumed agents being photoformed electron-hole pairs. The intensity dependence of the etch rate was determined separately for one-, two- and three-atom vacancies, leading to the conclusion that the corresponding photoprocesses involved one, two and three photons, respectively. A statistical analysis of the pair-distribution function for ejected adatoms gave evidence of an increase of ≳ 102in photoetching probability directly adjacent to a single-atom vacancy. Irradiation of the unchlorinated surface also resulted in adatom etching which increased linearly with fluence, but at a lower etch rate corresponding to photoetching with a cross-section of σe= 0.52 × 10−22cm2.

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The authors study a multiple chip-rate DS/CDMA system and its spreading code dependent performance. The multiple chip-rate technique is useful in some CDMA applications needing extra divisions among users in addition to code division to support variable data rate applications, such as multimedia systems. The study is applicable to both synchronous and asynchronous multiple chip-rate CDMA systems. A co-channel interference model based on correlation statistics for deriving bit error rate of a dual-chip-rate CDMA system is introduced considering various spreading codes, such as m-sequence, Gold, Gold-like, Kasami and Walsh codes. The results show that Gold code families are most suitable for the use in the dual-chip-rate CDMA system.

The authors propose a novel multiuser detection scheme for synchronous DS/CDMA systems, the orthogonal decision-feedback detector (ODFD), which performs equally well as the decorrelating decision-feedback detector (DDFD) but with a much reduced complexity. The ODFD employs a match filter bank matching to a set of orthonormal sequences which are generated by the Gram–Schmidt orthogonalisation procedure based on spreading codes. The ODFD algorithm involves only the orthonormal coefficient matrix which requires no frequent recalculations even when system parameters change. Successive decision-feedback detection is performed immediately at the output of the ODFD match filter bank without the transform matrix which is required in the DDFD.

The statistical correlation distribution convolution algorithm is introduced to study the performance of DS/CDMA indoor wireless systems. With the help of the algorithm, it is possible to obtain the bit error rate against number of simultaneous interfering transmitters, considering the effects of co-channel interference, Rayleigh multipath fading and power control schemes. The performance of two CDMA receivers, conventional correlator and equal-gain RAKE receiver, is compared. It is shown that the RAKE receiver can improve the system performance under the indoor multipath fading. However, its effectiveness under the power control is sensitive to the severity of multipath interference. When the multipath fading is rampant, a tight power control based on the main paths may not help improve the performance of the RAKE receiver.

Gordon–Mills–Welch (GMW) sequences possess a desirable two-valued autocorrelation function which helps a RAKE receiver track multipath returns. Unfortunately, their cross-correlation functions are less well controlled. Therefore, it is necessary to construct their subfamilies (taking advantage of its reasonably large family size) which offer satisfactory cross-correlation characteristics. The authors study several algorithms for constructing those quasi-optimal subfamilies in terms of minimised bit error rate under cochannel interference. The results show that performance of resultant subfamilies is very sensitive to the algorithms applied and subfamily sizes. A new criterion based on combined (even and odd) maximum cross-correlation is introduced for subfamily construction and two proposed highest-peak-deleting and most-peak-deleting algorithms are effective to construct the GMW quasi-optimal subfamilies.

In the paper a spreading code protocol (the code-sensing R3 code protocol) designed for wireless local networks is proposed and its performance is analysed. In a network adopting the protocol, destructive collisions among terminals are minimised by utilising the busy code-sensing and dual chip-rate techniques in transmissions of the REQ and ACK/data packets. A two-dimensional continuous-time Markov model is applied to study the behaviour of the protocol. The results show that a respectable improvement in throughput-delay performance can be achieved by the proposed protocol when compared to those previously reported in the literature.

The code protocol (the R3 protocol) for DS/SSMA wireless data networks is examined further and an analytical method is given of studying its delay and throughput bounds. In this protocol the communication-initiation process terminals uses handshaking packets (REQ and ACK packets), followed by the data packet. Different chip rates are utilised in transmissions of different packets to avoid destructive collisions between them. All packets are encoded by receiver-based codes. It is shown that the throughput lower bound of this protocol is about 0.24 when the normalised offered channel-traffic load is equal to one, and that the protocol offers stability to the network even at a very high offered channel-traffic load.

An unslotted DS/SSMA packet-radio protocol (the triple-receiver-based code (R3) protocol) suitable for code-division multiple-access (CDMA) wireless data networks is proposed. The communication between two data terminals is initiated by hand-shaking (request and acknowledgement stages) followed by data-packet transmission (pair-up stage), using the receiver-based signature codes for multiple-accessing. The two-dimensional continuous-time Markov chain was used to model and analyse the behaviour of the network. The analytical results show that a respectable improvement in throughput-delay performance can be achieved, applying the proposed protocol to unslotted DS/SSMA packet-radio networks, when compared to other reported code protocols.

In a situation such as a traffic accident on a highway, the active mobiles in an affected cell may easily outnumber the capacity, and an excessive increase in CDMA noise may, in the worst case, block all calls in the cell if the users insist on calling through the same cell site. A scheme to alleviate such congestion in CDMA cellular systems is proposed, so that traffic load is adaptively shed from affected cells by forced hand-offs of the mobiles farthest away from current cell site. The capacity with adaptive load shedding is studied by computer simulations considering two scenarios: a single congested cell with six neighbouring cells partially loaded, and three consecutive congested cells with four neighbouring cells partially loaded. The results show that the scheme offers higher CDMA cellular capacity gain than the normal power-up control adopted by the current CDMA cellular standard.

The temperature dependence of the electrical resistivity and the thermoelectric power (TEP) of Bi2Sr2—xLaxCaCu2Oy (x = 0 to 0.8) samples is reported. Analysis of the electrical resistivity of the insulating samples suggests that the conduction is governed by a variable-range-hopping mechanism in the low temperature range. The linear-T behavior of the superconducting samples is consistent with the Drude model. The broad peak shift in the S–T plot of the insulating samples is explained. The results of thermoelectric power are discussed following the two-band model.

Raman spectra have been studied on doped fullerides of BaxC60(x=3,4,6), AxBa3C60(x=0,3; A=K,Rb), and KxSm2.75C60(x=0,3.25). The results show different charge-transfer dependence of Raman shift of the two Ag modes in the t1u and t1g fullerides. Raman shift of Ag(2) mode with charge transfer in t1g fullerides does not follow a simple extrapolation from the low-doped t1u fullerides.

In a meta-analysis, we investigated effects of angiotensin receptor blockers (ARBs) in comparison to placebo or to other classes of antihypertensive drugs on endothelial function, as measured by brachial flow mediated vasodilation (FMD).

Packet conflicts in a distributed CDMA network vary with different code protocols which determine packet structure. Improperly designed packet structure is responsible for unrecoverable packet collisions in the channel, resulting in an unacceptably small throughput and large delay. A novel collision-channel model is presented to analyse the network performance concerning the packet contention nature for different CDMA code protocols.