Structure design and surface interference analysis of double crown surface configuration of multistage face gears

A novel transmission using the multistage face gears as the core component is used to realize variable speed with differential gear shifting, there are multiple face gears superimposed on the radial direction, meshing with planetary wheel at the same time, which achieves different outputs speed through braking different face gears. In order to solve the interference problems caused by asynchronous meshing motion between several face gears and the same cylinder gear, this study mainly focuses on the meshing theory study based on the double crown surfaces in tooth profile and tooth orientation. The surface structure of straight tooth and double crown are constructed according to the related surface equations, the corresponding interference conditions are obtained by comparison, every single stage face gear model is designed and assembled. This study shows that the double crown configuration surface structure can easily improve contact characteristics compared with straight tooth surface structure of face gear. In addition, the double crown configuration surface structure can improve the distribution and direction of contact path. This study is expected to establish a new tooth surface model, which can provide the best machining parameters for the face gears

Platelet and Immunity in Transfusion Medicine

Platelets are classically used in the clinic to maintain hemostasis, while recent evidence has shown the important role for platelets in the host inflammatory and immune responses. In fact, platelets in vivo produce different mediators such as cytokines or chemokines, which may be involved in the course of disease treatment, thus platelets transfusion is often an effective therapy in many cases. It is well known that platelets can regulate neutrophils, lymphocytes and other immune cells behavior in immune response, thus directing these immune cells onto the damaged tissues, organs or infected sites. On the other hand, platelets can induce neutrophil extracellular traps release in response to bacterial or viral infection. All the characterized novel profile of platelet, if not all, at least in some situations, should be take into consideration when platelets have to be transfused into patients

Effect of population migration and socioeconomic factors on the COVID-19 epidemic at county level in Guangdong, China

Coronavirus disease 2019 (COVID-19) has become a major public health concern worldwide. In this study, we aimed to analyze spatial clusters of the COVID-19 epidemic and explore the effects of population emigration and socioeconomic factors on the epidemic at the county level in Guangdong, China. Data on confirmed cases, population migration, and socioeconomic factors for 121 counties were collected from 1 December 2019 to 17 February 2020, during which there were a total of 1,328 confirmed cases. County-level infected migrants of Guangdong moving from Hubei were calculated by integrating the incidence rate, population migration data of Baidu Qianxi, and the resident population. Using the spatial autocorrelation method, we identified high-cluster areas of the epidemic. We also used a geographical detector to explore infected migrants and socioeconomic factors associated with transmission of COVID-19 in Guangdong. Our results showed that: 1) the epidemic exhibited significant positive global spatial autocorrelation; high–high spatial clusters were mainly distributed in the Pearl River Estuary region; 2) city-level population migration data corroborated with the incidence rate of each city in Hubei showed significant association with confirmed cases; 3) in terms of potential factors, infected migrants greatly contributed to the spread of COVID-19, which has strong ability to explain the COVID-19 epidemic; besides, the companies, transport services, residential communities, restaurants, and community facilities were also the dominant factors in the spread of the epidemic; 4) the combined effect produced by the intersecting factors can increase the explanatory power. The infected migrant factor interacted strongly with the community facility factor with the q value of 0.895. This indicates that the interaction between infected migrants and community facilities played an important role in transmitting COVID-19 at the county level

Morphology Engineering of Co₃O₄ Nanoarrays as Free-Standing Catalysts for Lithium–Oxygen Batteries

The effective shape-controlled synthesis of Co₃O₄ nanoarrays on nickel foam substrates has been achieved through a simple hydrothermal strategy. When they served as the binder- and conductive-agent-free porous cathodes for nonaqueous Li–O₂ batteries, they sufficiently reflect the favorable catalytic characteristic of Co₃O₄ and alleviate the problems of serious pore blocking and surface passivation caused by insoluble and insulating discharge products. In particular, Co₃O₄ rectangular nanosheets exhibit superior electrocatalytic performance comparing with Co₃O₄ nanowires and hexagonal nanosheets, leading to higher specific capacity and better cycling stability over 54 cycles at 100 mA g^–1, which relate to their good pore structure, large specific surface area, and highly active {112} exposed plane, effectively promoting the mass transport and reversible formation and decomposition of discharge products in the cathode. These comparisons further indicate the morphology effect of nanostructured Co₃O₄ on their performances as free-standing catalysts for Li–O₂ batteries, which also have been proved through the further analysis of discharge products on different shapes of Co₃O₄ nanoarrays electrodes

Study on the impact of bubble curtain on underwater acoustic communication

Conference Name:OCEANS 2014 - Taipei. Conference Address: Taipei, Taiwan. Time:April 7, 2014 - April 10, 2014.Bubble curtain technology has been applied in underwater blasting engineering for decaying the sound wave. Applying it to underwater acoustic countermeasure (UAC) is bound to achieve certain results. So it is important and necessary to assess the effect of bubble curtain on underwater acoustic (UWA) communication. In this paper, we commence from the bubble resonance theory and apply the Bellhop ray model in analyzing the bubble curtain which damps the impact signal at different depths and bubble curtain ranges and verify the correctness of the model. With this method, we get the impact of bubble curtain on underwater acoustic communication based on frequency shift keying (FSK) modulation by simulation and laboratory experiment

Characteristics and Relationships between Species Diversity and Productivity of Different Grassland Types in the Burqin Forest Region of the Altai Mountains

The Altai Mountain is located at the intersection of cold and arid regions. Climate change and overgrazing directly affect the growth of the grassland ecosystem in this region. This study took the grassland community in the Burqin forest area of the Altai Mountains as an example to analyze the species diversity and productivity of different grassland types based on 50 sampling plots. The relationship between species diversity and the productivity of grassland types at different altitudes was also discussed. The results showed that: (1) In the Burqin forest area, the desert steppe was dominated by Gramineae, Compositae, and Leguminosae. Montane steppe and mountain meadows were dominated by Umbelliferae, Gramineae, and Liliaceae. Gramineae, Ranunculaceae, and Liliaceae were the dominant families in both montane meadows steppe and alpine steppe but occurred in varying proportions. (2) The variation in plant numbers at the family–species level was characterized as montane steppe > alpine meadow > montane meadow steppe > desert steppe > mountain meadows. (3) The similarity in species composition among communities of different grassland types was low. In DS and MM, the number of grasslands and species played a decisive role in determining the biomass. The biomass of MS and AM was determined using the Simpson and Shannon–Wiener indices, and the number of dominant species determined the biomass. The number of grasslands and species did not have a significant impact on the biomass of MMS, which may be due to human factors such as grazing. (4) The dominant species in the grassland at an altitude of 1200–1400 m is prominent. The number of individuals in the dominant species was large and evenly distributed. Margalef peaked at an altitude of 1600–1800 m, but the number of individuals was small, resulting in low biomass and diversity in this range. Most plants survive at an altitude of 2000–2200 m; therefore, in grassland protection and planning management, it is important to consider the specific situation of plant growth under different habitats at different altitudes and make reasonable protection decisions based on local conditions to maintain species diversity and sustainable development of grassland ecosystems. This study provides basic data to support the theoretical basis for the protection and sustainable utilization of grassland resources and the restoration of degraded grasslands in the study region

Free-Standing Three-Dimensional Graphene/Manganese Oxide Hybrids As Binder-Free Electrode Materials for Energy Storage Applications

Novel three-dimensional (3D) hybrid materials, i.e., free-standing 3D graphene-supported MnO₂ nanosheets, are prepared by a simple and controllable solution-phase assembly process. Characterization results show that MnO₂ nanosheets are uniformly anchored on a 3D graphene framework with strong adhesion and the integral hybrids show desirable mechanical strength. Such unique structure of 3D graphene/MnO₂ hybrids thus provides the right characteristics of binder-free electrode materials and could enable the design of different kinds of high-performance energy storage devices. Especially, an advanced asymmetric supercapacitor is built by using a 3D graphene/MnO₂ hybrid and a 3D graphene as two electrodes, and it is able to work reversibly in a full operation voltage region of 0–3.5 V in an ionic liquid electrolyte and thus exhibits a high energy density of 68.4 Wh/kg. As the cathode materials for Li–O₂ and Li–MnO₂ batteries, the 3D graphene/MnO₂ hybrids exhibit outstanding performances, including good catalytic capability, high reversible capacity and desirable cycling stability. The results presented here may pave a way for new promising applications of such 3D graphene/MnO₂ hybrids in advanced electrochemical energy storage devices

Autocorrelation method for time delay estimation to calculate the source level of click signal for Sousa Chinensis

Conference Name:OCEANS 2014 - Taipei. Conference Address: Taipei, Taiwan. Time:April 7, 2014 - April 10, 2014.Like other dolphins, Sousa Chinensis produces click signals to echolocate in underwater. Research on the source level (SL) of click signal transmitted by Sousa Chinensis is beneficial to understand the survival and behavior of such animals. In the shallow sea where the Sousa Chinensis lives, the underwater environment is so complex that causes the click signals propagation to the receiving hydrophone at different times in different paths. In this paper, we introduced autocorrelation signal process analysis to calculate the delay time, predicted the source level base on the oretical sound wave attenuation rule in the sea. During May of 2013, the Click signals were recorded by a set of hydrophone system in shallow sea of Xiamen in China. The results show that the SL of Sousa Chinensis ranges from 166.9 to 199.6 dB peak to peak (p-p) re: 1μPa, and mean value is 180.05±8.93dB