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A certain amount of H 3 BO 3 was preheated at 120 °C for 8 h in order to obtain HBO 2 for preparation of TiB 2 powders by carbothermal reduction. The influence of different amounts of HBO 2 ( 44.9–48.4 wt%), calcination temperature (1400–1800 °C) and the variety of boron sources (H 3 BO 3 , HBO 2 and B 2 O 3 ) on the composition and microstructure of the product was investigated. The resultant powders were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Results showed that impurity-free TiB 2 crystalline powders with the grain size of about 10.0 μm could be successfully prepared at 1700 °C for 30 min in Ar atmosphere when the amount of HBO 2 was 46.7 wt%. Compared with control groups, grains of powders revealed better crystallinity and relatively finer particle size.

Submicrometric TiB 2 powders were synthesized by carbothermal reduction process using titanium dioxide, boron carbide and carbon black as the starting materials. The influence of different amount of boron carbide (22.0–26.8 wt%), calcination temperature (1400–1900 °C) and holding time (15–90 min) on the composition and microstructure of the product was investigated. The resultant powders were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Results showed that hexagonal impurity-free TiB 2 crystalline powders with the grain size below 1.0 μm could be successfully prepared at 1600 °C for 30 min in Ar atmosphere when the amount of boron carbide was 25.3 wt%. The increase in temperature contributed to reaction completion and grain growth, but the abnormal grain growth and oversintering took place above 1800 °C.

Although magnesium phosphate cement (MPC) is a type of chemically bonded ceramic with many vital properties, the practical application is limited by the high cost of raw materials. Dead burned MgO generally obtained from calcination of magnesite is used in MPC production. Dolomite as another abundant magnesium resource is widely distributed and has larger deposits than magnesite. This paper aims to replace magnesite with dolomite as raw materials to reduce the cost in MPC production. Quartz powders were also introduced in the calcination process to chemically combine with CaO components in dolomite. The effect of calcination temperature and dolomite-to-quartz mass ratio on the properties of calcined raw material were investigated. After calcination, the influence of dolomite-quartz powders under different calcination conditions on the performance of MPC pastes was assessed by observing the setting time, compressive strength, phase development and microstructure of hydration products as well as soundness. The calcination model of fine dolomite particles and coarse quartz particles was proposed to guarantee less free-CaO and more MgO after calcination. When the setting time of MPC prepared by the sample T1250-R1.5 was 16 min, the compressive strength of the pastes could reach 22 MPa at curing age of 3 h and 63 MPa at 7 d, with sufficient soundness and safety by preliminary judgment. The relatively lower calcination temperature at 1250 °C compared to conventionally prepared dead burnt magnesite would significantly reduce energy consumption and operating costs in production of magnesium bearing raw material for MPC.

Natural food-derived hypoglycemic molecules hold potential for decreasing the postprandial increase in blood glucose and preventing type 2 diabetes along with its associated comorbidities. This study investigated the inhibitory effects of Lonicera caerulea berry polyphenols (LCBP) on the activity of α-amylase and the involved mechanisms. We used an enzyme inhibition assay, enzyme kinetics analysis, fluorescence quenching, and molecular docking to assess the effects of LCBP and its primary constituents. LCBP significantly inhibited the activity of α-amylase (IC50 301.5 μg/mL) and exhibited a higher inhibitory effect than acarbose, a positive control for carbohydrate digestion. The enzyme kinetics and Lineweaver−Burk plot analyses revealed a reversible competitive inhibition of α-amylase activity by LCBP and its main constituent components cyanidin-3-glucoside (C-3-G), catechins, and chlorogenic acid (CA). Fluorescence quenching experiments revealed that LCBP exerted a dose-dependent quenching effect on α-amylase and produced an emission wavelength redshift due to static quenching. The computer simulation-assisted molecular docking study showed that the binding of C-3-G, catechins, and CA disrupts enzyme conformation, while the formation of the polyphenol-enzyme complex inhibits enzyme activity. Together, these results suggest that LCBP effectively reduces postprandial hyperglycemia and type 2 diabetes and thus, exhibits potential for application as a functional food additive.

Recently, Deep Learning (DL), especially Convolutional Neural Network (CNN), develops rapidly and is applied to many tasks, such as image classification, face recognition, image segmentation, and human detection. Due to its superior performance, DL-based models have a wide range of application in many areas, some of which are extremely safety-critical, e.g. intelligent surveillance and autonomous driving. Due to the latency and privacy problem of cloud computing, embedded accelerators are popular in these safety-critical areas. However, the robustness of the embedded DL system might be harmed by inserting hardware/software Trojans into the accelerator and the neural network model, since the accelerator and deploy tool (or neural network model) are usually provided by third-party companies. Fortunately, inserting hardware Trojans can only achieve inflexible attack, which means that hardware Trojans can easily break down the whole system or exchange two outputs, but can't make CNN recognize unknown pictures as targets. Though inserting software Trojans has more freedom of attack, it often requires tampering input images, which is not easy for attackers. So, in this paper, we propose a hardware-software collaborative attack framework to inject hidden neural network Trojans, which works as a back-door without requiring manipulating input images and is flexible for different scenarios. We test our attack framework for image classification and face recognition tasks, and get attack success rate of 92.6% and 100% on CIFAR10 and YouTube Faces, respectively, while keeping almost the same accuracy as the unattacked model in the normal mode. In addition, we show a specific attack scenario in which a face recognition system is attacked and gives a specific wrong answer., 6 pages, 8 figures, 5 tables, accepted to ISVLSI 2018

Convolutional Neural Network (CNN) has become the state-of-the-art algorithm for many computer vision tasks. But its high computation complexity and high memory complexity makes it hard to be deployed on traditional platforms like CPUs. Memory energy can take up a large part of the system energy, which limits the energy efficiency of CNN processing. The emerging metal-oxide resistive switching random-access memory (RRAM) has been widely studied because of its good properties like high storage density and the compatibility with CMOS. In this paper, a system level energy analysis of using RRAM as on-chip weight buffer is carried out for a typical CNN accelerator. Hardware and scheduling optimizations are proposed to fully utilize the large RAM and avoid high read/write energy overhead. Experimental results show that RRAM based designs save 12-18% system energy with 15-75% smaller on-chip RAM area compared with SRAM designs.

In recent years, Convolutional Neural Network (CNN) has been widely applied in computer vision tasks and has achieved significant improvement in image object detection. The CNN methods consume more computation as well as storage, so GPU is introduced for real-time object detection. However, due to the high power consumption of GPU, it is difficult to adopt GPU in mobile applications like automatic driving. The previous work proposes some optimizing techniques to lower the power consumption of object detection on mobile GPU or FPGA. In the first Low-Power Image Recognition Challenge (LPIRC), our system achieved the best result with mAP/Energy on mobile GPU platforms. We further research the acceleration of detection algorithms and implement two more systems for real-time detection on FPGA with higher energy efficiency. In this paper, we will introduce the object detection algorithms and summarize the optimizing techniques in three of our previous energy efficient detection systems on different hardware platforms for object detection.

ZrB2–SiC composite powders were synthesized in situ via carbothermal reduction using ZrO2, HBO2 and carbon black as the starting materials. The influences of HBO2 contents (40.6–45.5 wt%), boron sources (HBO2, H3BO3 and B2O3) and carbon sources (black carbon, activated carbon, graphite and petroleum coke) on phase composition and morphology of ZrB2–SiC composite powders were analyzed. The obtained samples were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Results showed that when the HBO2 content was 43.2 wt%, impurity-free ZrB2–SiC composite powders could be successfully produced at 1600 °C for 90 min in argon atmosphere. Meanwhile, columnar ZrB2 and granular SiC particles were combined interactively. Compared with control groups, products fabricated via black carbon revealed the better crystallinity and finer particle size.

We derive stellar population parameters for a representative sample of ultracompact dwarfs (UCDs) and a large sample of massive globular clusters (GCs) with stellar masses $\gtrsim$ 10$^{6}$ $M_{\odot}$ in the central galaxy M87 of the Virgo galaxy cluster, based on model fitting to the Lick-index measurements from both the literature and new observations. After necessary spectral stacking of the relatively faint objects in our initial sample of 40 UCDs and 118 GCs, we obtain 30 sets of Lick-index measurements for UCDs and 80 for GCs. The M87 UCDs have ages $\gtrsim$ 8 Gyr and [$\alpha$/Fe] $\simeq$ 0.4 dex, in agreement with previous studies based on smaller samples. The literature UCDs, located in lower-density environments than M87, extend to younger ages and smaller [$\alpha$/Fe] (at given metallicities) than M87 UCDs, resembling the environmental dependence of the Virgo dE nuclei. The UCDs exhibit a positive mass-metallicity relation (MZR), which flattens and connects compact ellipticals at stellar masses $\gtrsim$ 10$^{8}$ $M_{\odot}$. The Virgo dE nuclei largely follow the average MZR of UCDs, whereas most of the M87 GCs are offset towards higher metallicities for given stellar masses. The difference between the mass-metallicity distributions of UCDs and GCs may be qualitatively understood as a result of their different physical sizes at birth in a self-enrichment scenario or of galactic nuclear cluster star formation efficiency being relatively low in a tidal stripping scenario for UCD formation. The existing observations provide the necessary but not sufficient evidence for tidally stripped dE nuclei being the dominant contributors to the M87 UCDs., Comment: 13 pages, accepted by ApJ

In recent years, Convolutional Neural Network (CNN) has been widely applied in computer vision tasks. FPGAs have been widely explored to accelerate CNNs due to its high performance, high energy efficiency, and flexibility. By fusing multiple layers in CNN, the intermediate data transfer can be reduced. With a faster algorithm using Winograd transformation, the computation of convolution can be further accelerated. However, previous accelerators with cross-layer or Winograd algorithm are designed for a particular CNN model. The FPGA should be reprogrammed when running another CNN model on the hardware. In this work, we design an instruction driven CNN accelerator supporting Winograd algorithm and cross-layer scheduling. We firstly modify the cross-layer loop unrolling order to extract basic operations as instructions, and then improve the on-chip memory architecture for higher computation units utilization rate in Winograd. We evaluate the hardware architecture and scheduling policy on Xilinx Virtex-7 690t FPGA platform. As a case study, the intermediate data transfer can be reduced by over 90% on VGG-D CNN model with cross-layer policy. The performance of our hardware accelerator reaches 1500 GOP/s. Experimental results show that our design achieves a 7 χ speed-up than previous cross-layer FPGA accelerator on the same platform. The performance can be further improved by 78% if larger Winograd transformation sizes are used.

A recent switch in the study of the beginning of agriculture is to demonstrate the increasingly closer interaction between people and the landscape and how this would have played a crucial role in the transition to agriculture. Understanding the palaeo-ecology of the local environments at key sites and its relationship with subsistence strategies is critical to an improved appreciation of such interactions. This article examines macro- and micro-plant remains discovered at two important sites in North China, both dated to around 10,000 cal. yr BP. These two sites, Zhuannian and Nanzhuangtou, are located on the terrace of the Bai River in the Yan Mountains and next to Baiyangdian Lake on the piedmont of the Taihang Mountains, respectively. The floral remains at these two sites provide a great opportunity to examine (1) post-Pleistocene subsistence strategies, (2) the increasing consumption of millets and grassy plants and its significance and (3) the intra-regional diversity in food exploitation and its relationships with local environments. While the macro-plant remains at Nanzhuangtou indicate the importance of aquatic plants in the palaeo-diet, those at Zhuannian suggest a tendency of exploiting tree plants. This significance of these diversified plant food exploitation strategies by the last hunter-gatherers should be paid more attention in future research. Our data also once again confirm the importance of millet consumption to these hunter-gatherers on the eve of millet domestication.

Direct-drive robotics is quite attractive because of its high efficiency, high robustness and wide application prospect. This paper is to propose a new double-stator hybrid flux switching permanent magnet (DSH-FSPM) machine for the direct-drive robotic applications. The key is to integrate the distinct merits of high torque density, flux-modulation capability, high fault-tolerant capacity and low torque ripple together. First, the machine design and flux switching principle are analyzed to illuminate the basic operation principle. Also the machine performance shows that the inner and outer torque ripples offset with each other and contribute to the low torque ripple less than 7%. Furthermore, with the addition of the DC current, the machine flux and EMF can be weakened, which can enlarge the flexibility and stability for the machine operation. The performances of the machine verify the feasibility of the new topology for the direct-drive robotics.

We compare the existent methods including the minimum spanning tree based method and the local stellar density based method, in measuring mass segregation of star clusters. We find that the minimum spanning tree method reflects more the compactness, which represents the global spatial distribution of massive stars, while the local stellar density method reflects more the crowdedness, which provides the local gravitational potential information. It is suggested to measure the local and the global mass segregation simultaneously. We also develop a hybrid method that takes both aspects into account. This hybrid method balances the local and the global mass segregation in the sense that the predominant one is either caused either by dynamical evolution or purely accidental, especially when such information is unknown a priori. In addition, we test our prescriptions with numerical models and show the impact of binaries in estimating the mass segregation value. As an application, we use these methods on the Orion Nebula Cluster (ONC) observations and the Taurus cluster. We find that the ONC is significantly mass segregated down to the 20th most massive stars. In contrast, the massive stars of the Taurus cluster are sparsely distributed in many different subclusters, showing a low degree of compactness. The massive stars of Taurus are also found to be distributed in the high-density region of the subclusters, showing significant mass segregation at subcluster scales. Meanwhile, we also apply these methods to discuss the possible mechanisms of the dynamical evolution of the simulated substructured star clusters., 14 pages, 13 figures. minor changes, matches published version

In the present, unmanned aerial vehicles (UAV) has arisen more and more attention due to the high efficiency, ease and safety in completing complex missions [1][2].

Early pottery sherds excavated in northern China date back to more than 11,000 cal a BP, and are presumed to have been used as cooking vessels. There has been, however, no direct evidence to demonstrate this function. Here we report ancient starch grains recovered from carbonized residues adhering to the bases of flat-bottomed vessels excavated from the Zhuannian site dating more than 10,000 cal a BP in the North China Plain. This evidence demonstrates that early pottery was being used to cook cereal grains, particularly millets, and acorns. Because millets were in the process of domestication at this time, we propose that pottery invention in northern China may have been related to early farming activities.

The exact mathematical modeling of electric machines has always been an effective tool for scholars to understand the working principles and structure requirements of novel machine topologies. This paper provides an analytical modeling method—the harmonic modeling method (HMM)—for two types of consequent-pole magnetic-geared machines, namely the single consequent-pole magnetic-geared machine (SCP-MGM) and the dual consequent-pole magnetic-geared machine (DCP-MGM). By dividing the whole machine domain into different ring-like subdomains and solving the Maxwell equations, the magnetic field distribution and electromagnetic parameters of the two machines can be obtained, respectively. The two machines were applied in the propulsion systems of hybrid electric vehicles (HEVs). The electromagnetic performances of two machines under different operating conditions were also compared. It turns out that the DCP-MGM can reach a larger electromagnetic torque compared to that of the SCP-MGM under the same conditions. Finally, the predicted results were verified by the finite element analysis (FEA). A good agreement can be observed between HMM and FEA. Furthermore, HMM can also be applied to the mathematical modeling of other consequent-pole electric machines in further study.

Real-time pedestrian detection and tracking are vital to many applications, such as the interaction between drones and human. However, the high complexity of Convolutional Neural Network (CNN) makes them rely on powerful servers, thus is hard for mobile platforms like drones. In this paper, we propose a CNN-based real-time pedestrian detection and tracking system, which can achieve 14.7 fps detection and 200 fps tracking with only 3W.

In recent years, convolutional neural network (CNN) based methods have achieved great success in a large number of applications and have been among the most powerful and widely used techniques in computer vision. However, CNN-based methods are com-putational-intensive and resource-consuming, and thus are hard to be integrated into embedded systems such as smart phones, smart glasses, and robots. FPGA is one of the most promising platforms for accelerating CNN, but the limited bandwidth and on-chip memory size limit the performance of FPGA accelerator for CNN.In this paper, we go deeper with the embedded FPGA platform on accelerating CNNs and propose a CNN accelerator design on embedded FPGA for Image-Net large-scale image classification. We first present an in-depth analysis of state-of-the-art CNN models and show that Convolutional layers are computational-centric and Fully-Connected layers are memory-centric.Then the dynamic-precision data quantization method and a convolver design that is efficient for all layer types in CNN are proposed to improve the bandwidth and resource utilization. Results show that only 0.4% accuracy loss is introduced by our data quantization flow for the very deep VGG16 model when 8/4-bit quantization is used. A data arrangement method is proposed to further ensure a high utilization of the external memory bandwidth. Finally, a state-of-the-art CNN, VGG16-SVD, is implemented on an embedded FPGA platform as a case study. VGG16-SVD is the largest and most accurate network that has been implemented on FPGA end-to-end so far. The system on Xilinx Zynq ZC706 board achieves a frame rate at 4.45 fps with the top-5 accuracy of 86.66% using 16-bit quantization. The average performance of convolutional layers and the full CNN is 187.8 GOP/s and 137.0 GOP/s under 150MHz working frequency, which outperform previous approaches significantly.

We describe the target selection algorithm for the low latitude disk portion of the LAMOST Pilot Survey, which aims to test systems in preparation for the LAMOST spectroscopic survey. We use the PPMXL (Roeser et al. 2010) astrometric catalog, which provides positions, proper motions, B/R/I magnitudes (mostly) from USNO-B (Monet et al. 2003) and J/H/Ks from The Two Micron All Sky Survey (2MASS, see Skrutskie et al. 2006) as well. We chose 8 plates along the Galactic plane, in the region $0^\circ

It is generally understood that foxtail millet and broomcorn millet were initially domesticated in Northern China where they eventually became the dominant plant food crops. The rarity of older archaeological sites and archaeobotanical work in the region, however, renders both the origins of these plants and their processes of domestication poorly understood. Here we present ancient starch grain assemblages recovered from cultural deposits, including carbonized residues adhering to an early pottery sherd as well as grinding stone tools excavated from the sites of Nanzhuangtou (11.5–11.0 cal kyBP) and Donghulin (11.0–9.5 cal kyBP) in the North China Plain. Our data extend the record of millet use in China by nearly 1,000 y, and the record of foxtail millet in the region by at least two millennia. The patterning of starch residues within the samples allow for the formulation of the hypothesis that foxtail millets were cultivated for an extended period of two millennia, during which this crop plant appears to have been undergoing domestication. Future research in the region will help clarify the processes in place.

The processes that led to the transition from small mobile groups of hunter-gatherers in the Late Pleistocene to sedentary communities of the Early Holocene in north China are poorly understood. The Donghulin site in Beijing was occupied at the onset of the Holocene, and excavations have revealed a rich archaeological record for investigating the changing subsistence strategies during this transitional period. A functional study of two grinding stones (a slab and a handstone) near a burial dated to 9220–8750 cal BC at Donghulin investigated the range of plants exploited during this early occupation period. Starch residues indicate that the grinding stones were used for processing plants, and confirm processing of acorns, which is consistent with the incidence of oak in the pollen record. The usewear, with only rare patches of developed polish, suggests that plant parts of low silica content were processed, although usewear on the handstone suggests processing of two or more plant taxa. The results suggest that the use of grinding stones to process plant foodstuffs, particularly acorns, may have played a major role in the subsistence strategy during the transitional period to sedentism and agriculture in some parts of north China.

The conventional wisdom has been challenged recently that microblades with handles are only tools for hunting and gathering in the Neolithic Age. Some scholars argued that microblades actually played an important part in the early agricultural development in the Neolithic. However, both of these opinions lacked direct evidence. Environmental scanning electron microscopy (ESEM) is used to analyze the residues of the bone-handled microblade excavated at the Shangzhai site in Pinggu, Beijing. The ESEM observation and EDX analysis show that at the edge of this bone-handled microblade are Ca, P, C, O or C, N, O, etc, which provide direct evidence for determining its function, namely that this microblade may have been dealt with animals. In addition, there was a layer of glue at the back of the microblade with barium and zinc salt distributed evenly in it, this new discovery sheds new light on adhesive technology in ancient China.

Prehistoric groundstone tools including slabs (metate, mo-pan) and mullers (mano, mo-bang) are often considered to be tools that were used to process cereals in ancient China. Most archaeologists believe that groundstone tools are indicators of an agrarian economy. This study employed starch grain analysis to examine a slab and a muller excavated from the Shangzhai Site (7500-7000 cal a BP), Beijing. Identifiable starch grains recovered from the stone tools were classified into 9 genera and 12 species, most of which were from acorns and foxtail millets. Remains from the oak species Q. mongolicus, Q. acuttssima, and Q. dentate were identified as well as a few starch grains from broomcorn (Panicum miliaseum) and bean (Vigna sp.). Other starch grains were from unidentifiable roots and grasses. A variety of starch grains indicates that the grinding stone tools were used to process not only cereals, but also other seeds or roots that had to be ground or husked, thus bringing into question the aforementioned cereal hypothesis. Because the numbers of starch grains from nuts and millets were so large, both gathering and cultivation might have been important economic patterns before 7000 years ago in Beijing area. Moreover, the starch remains are derived from plants that indicate that the paleoclimate of Beijing was wetter and warmer than today’s.

We report here on the isotopic analysis of the diet of one of the oldest modern humans found in Eurasia, the Tianyuan 1 early modern human dating to ≈40,000 calendar years ago from Tianyuan Cave (Tianyuandong) in the Zhoukoudian region of China. Carbon and nitrogen isotope analysis of the human and associated faunal remains indicate a diet high in animal protein, and the high nitrogen isotope values suggest the consumption of freshwater fish. To confirm this inference, we measured the sulfur isotope values of terrestrial and freshwater animals around the Zhoukoudian area and of the Tianyuan 1 human, which also support the interpretation of a substantial portion of the diet from freshwater fish. This analysis provides the direct evidence for the consumption of aquatic resources by early modern humans in China and has implications for early modern human subsistence and demography.

We investigate the evolution of young star clusters using N-body simulations. We confirm that subvirial and fractal-structured clusters will dynamically mass segregate on a short timescale (within 0.5 Myr). We adopt a modified minimum-spanning-tree (MST) method to measure the degree of mass segregation, demonstrating that the stars escaping from a cluster's potential are important for the temporal dependence of mass segregation in the cluster. The form of the initial velocity distribution will also affect the degree of mass segregation. If it depends on radius, the outer parts of the cluster would expand without undergoing collapse. In velocity space, we find 'inverse mass segregation,' which indicates that massive stars have higher velocity dispersions than their lower-mass counterparts., Comment: 13 pages and 6 figures based on 14 .eps files

These are few sites about 10 000 BP in the early Neolithic period in North China; among these, the Donghulin site is the only one which included the remains of peoples' use of fire (hearth pits), stone implements, pottery objects, and human tombs. The excavation of the Donghulin site in 2001 provides very important information for research on people and culture in the early Neolithic period in North China. The finding of Donghulin Man has filled the gap in our knowledge of human development since the period of the "Upper Cave Man" (30 000a BP) in North China. It is also important for research on people-land relationships. Na severu Kitajske je nekaj zgodnjeneolitskih najdišč iz časa okoli 10 000 BP. Med njimi je najdišče Donghulin edino, kjer so našli ostanke človekove uporabe ognja (jame za ognjišča), kamnito orodje, keramiko in človeške grobove. Izkopavanja najdišča Donghulin leta 2001 so dala pomembne podatke o ljudeh in kulturi v zgodnjem neolitiku na severu Kitajske. Najdba človeka Donghulin je zapolnila našo vrzel v poznavanju razvoja človeka od časa "Upper Cave Man" (30 000a BP) na severnem Kitajskem. Najdišče je pomembno tudi za raziskovanje povezave med človekom in pokrajino.

We use samples of local main-sequence stars to show that the radial gradient of [Fe/H] in the thin disk of the Milky Way decreases with mean effective stellar temperature. Many of these stars are visiting the solar neighborhood from the inner and outer Galaxy. We use the angular momentum of each star about the Galactic center to determine the guiding center radius and to eliminate the effects of epicyclic motion, which would otherwise blur the estimated gradients. We interpret the effective temperature as a proxy for mean age, and conclude that the decreasing gradient is consistent with the predictions of radial mixing due to transient spiral patterns. We find some evidence that the trend of decreasing gradient with increasing mean age breaks to a constant gradient for samples of stars whose main-sequence life-times exceed the likely age of the thin disk., Comment: Accepted to appear in ApJ, 8 pages, 8 figures