Groove-type channel enhancement-mode Al GaN/GaN MIS HEMT with combined polar and nonpolar AlGaN/GaN heterostructures

A novel groove-type channel enhancement-mode AlGaN/GaN MIS high electron mobility transistor（GTCE-HEMT）with a combined polar and nonpolar AlGaN/GaN heterostucture is presented. The device simulation shows a threshold voltage of 1.24 V, peak transconductance of 182 m S/mm, and subthreshold slope of 85 m V/dec, which are obtained by adjusting the device parameters. Interestingly, it is possible to control the threshold voltage accurately without precisely controlling the etching depth in fabrication by adopting this structure. Besides, the breakdown voltage（VB） is significantly increased by 78% in comparison with the value of the conventional MIS-HEMT. Moreover, the fabrication process of the novel device is entirely compatible with that of the conventional depletion-mode（D-mode） polar AlGaN/GaN HEMT. It presents a promising way to realize the switch application and the E/D-mode logic circuits.

Effects of slow or controlled release fertilizer types and fertilization modes on yield and quality of rice

There is limited information about the influence of slow or controlled release fertilizer（S/CRF） on rice yield and quality. In this study, japonica rice cultivar Nanjing 9108 was used to study the effects of three different S/CRFs（polymer-coated urea（PCU）, sulfur-coated urea（SCU）, and urea formaldehyde（UF）） and two fertilization modes（both S/CRF and common urea（CU） as basal fertilizer, S/CRF as basal and CU as tillering fertilizer） on rice yield and quality. CU only was applied separately as control（CK）. Results showed that, rice grain yield, chalky kernel rate, chalky area, overall chalkiness, and the content of gliadin, glutenin, and protein, all showed the trends of UF〉PCU〉SCU within the same fertilization mode, and showed the trends of S/CRF as basal and CU as tillering fertilizer〉both S/CRF and CU as basal fertilizer within the same type of S/CRF. In contrast, the contents of amylose, amylopectin, and starch, as well as taste value, and peak and hot viscosity showed trends of SCU〉PCU〉UF, and the trends of both S/CRF and CU as basal fertilizer〉S/CRF as basal and CU as tillering fertilizer. Among S/CRF treatments and fertilization modes, taste values of cooked rice were positively correlated with amylose, amylopectin, and starch contents, as well as gel consistency, peak viscosity, hot viscosity, and cool viscosity, while negatively correlated with globulin, gliadin, glutenin, and protein contents. The types of S/CRF and fertilization modes are important for improving rice yield and quality. Compared to CK, higher yield and similar quality of rice was achieved with UF as basal and CU as tillering fertilizer, and similar yield with improved appearance and eating and cooking quality of rice was achieved with either both UF and CU as basal fertilizer, or PCU as basal and CU as tillering fertilizer.

Fabrication of 16W all-normal-dispersion mode-locked Yb-doped rod-type fiber laser with large-mode area

A mode-locked ytterbium-doped rod-type fiber laser with 85 ~tm core diameter is developed based on the nonlinear polarization evolution in an all-normal-dispersion ring cavity, in which a uniaxial birefringent plate is used as the spectral filter. Average power up to 16 W is obtained at the repetition rate of 58 MHz, and the pulse duration is compressed to 182 fs with a grating-pair compressor. The output laser pulses show very good beam quality and power stability.

Complete eigenmode analysis of a ladder-type multiple-gap resonant cavity

A theoretical model is developed for calculating the eigenmodes of the multi-gap resonant cavity. The structure of concern is a kind of ladder-type circuit, offering the advantages of easy fabrication, high characteristic impedance （R/Q）, and thermal capacity in the millimeter wave to THz regime. The eigenfunction expansion method is used to establish the field expressions for the gaps and the coupling region. Then, the match conditions at the interface are employed, which leads to a group of complicate boundary equations in the form of an infinite series. To facilitate the mathematical treatments and perform a highly efficient calculation, these boundary equations are transformed into the algebraic forms through the matrix representations. Finally, the concise dispersion equation is obtained. The roots of the dispersion equation include both the axial modes in the gaps, which include the fundamental and the high-order modes, and the cavity modes in the coupling region. Extensive numerical results are presented and the behaviors of the multi-gap resonant cavity are examined.

Controlling chaos based on a novel intelligent integral terminal sliding mode control in a rod-type plasma torch

An integral terminal sliding mode controller is proposed in order to control chaos in a rod-type plasma torch system.In this method, a new sliding surface is defined based on a combination of the conventional sliding surface in terminal sliding mode control and a nonlinear function of the integral of the system states. It is assumed that the dynamics of a chaotic system are unknown and also the system is exposed to disturbance and unstructured uncertainty. To achieve a chattering-free and high-speed response for such an unknown system, an adaptive neuro-fuzzy inference system is utilized in the next step to approximate the unknown part of the nonlinear dynamics. Then, the proposed integral terminal sliding mode controller stabilizes the approximated system based on Lyapunov＇s stability theory. In addition, a Bee algorithm is used to select the coefficients of integral terminal sliding mode controller to improve the performance of the proposed method. Simulation results demonstrate the improvement in the response speed, chattering rejection, transient response,and robustness against uncertainties.

电压模式Buck变换器type 3A型补偿器的研究

针对电压模式Buck型开关电源type 3A型补偿器进行研究.对type 3A型补偿网络的穿越频率进行详细的推导,并得出该穿越频率与负载电流无关.在输入电压和输出电压发生较大变化时,只需调节补偿网络外部电容Cff,就能得到良好的相位裕度和环路稳定性.采用Matlab和Hspice对环路进行仿真,仿真结果验证了对type 3A型补偿器理论研究的合理性.

永磁同步电机自适应高阶滑模Type-2模糊控制

针对永磁同步电机数学模型不确定问题,提出一种自适应高阶滑模Type-2模糊控制方法。采用积分滑模面二阶滑模控制律,保持传统滑模控制的鲁棒性并实现不含不确定高阶输入输出有限时间稳定;不需要预先确定干扰与不确定上边界,利用Lyapunov理论获得自适应调节Type-2模糊规则生成Super-Twisting信号削弱抖振。仿真结果表明永磁同步电机具有良好的跟踪性能,同时验证了该方法的可行和有效性。

Research on Development Mode of Rural Tourism Based on Experience

In view of the changes of tourism industry in the background of experience economy, and starting from the perspective that the emotional needs of tourists were boosting and they had paid increasing attention upon experience during the process of travelling, this research tried to find out a new development mode of rural tourism which took identification of tourism resource , subdivision of target market, designing of experience projects and personnel training into consideration. In the process of development, designing and implementation, it emphasized the definiteness of development direction, construction of unique theme, creation of experience atmosphere, showing tourists the charm of countryside in a full and deep way, and consequently highlighted the cultural, recreational and regional feature of rural tourism. What's more, it should satisfy tourists' emotional needs with emotional, interactive and personalized tourist products, leave tourists unique experience and good memories, prolong tourists' stay and enhance their loyalty, so as to generate higher economic benefits, promote rural economic growth and construct harmonious new countryside.

Analysis of the Development Mode Evolution of Holiday Resorts in Suburban Areas of Beijing City

To study the investment activities of tourism developers in suburban tourism destinations of metropolis.421 holiday resorts around Beijing City are selected to study the evolution process of their economic types and development modes.The results show that the development mode of holiday resorts in suburban Beijing is guided by state investment,collectively operated by rural residents,and supplemented by private or other investment types.

Comparative Study and Inspiration of Management Mode of Heritage Tourist Attractions in China and Foreign Countries

In order to improve the management level of heritage tourist attractions and achieve their sustainable development,a comparative study has been conducted on the management mode of heritage tourist attractions in China and foreign countries from the perspective of management foundation,management objects and management resources.Then,suggestions have been proposed from the ideology and supervision mechanism,including improving ideology,upgrading management system,completing supervision mechanism and adopting international management mode.Particularly,the paper has pointed out that it should find the best management mode based on different social and economic backgrounds of the countries of heritage tourist attractions.

Tight sandstone gas accumulation mechanism and development models

Tight sandstone gas serves as an important unconventional hydrocarbon resource, and outstanding results have been obtained through its discovery both in China and abroad given its great resource potential. However, heated debates and gaps still remain regarding classification standards of tight sandstone gas, and critical controlling factors, accumulation mechanisms, and devel- opment modes of tight sandstone reservoirs are not deter- mined. Tight sandstone gas reservoirs in China are generally characterized by tight strata, widespread distri- bution areas, coal strata supplying gas, complex gas-water relations, and abnormally low gas reservoir pressure. Water and gas reversal patterns have been detected via glass tube and quartz sand modeling, and the presence of critical geological conditions without buoyancy-driven mecha- nisms can thus be assumed. According to the timing of gas charging and reservoir tightening phases, the following three tight sandstone gas reservoir types have been identified： （a） ＂accumulation-densification＂ （AD）, or the conventional tight type, （b） ＂densification-accumulation＂ （DA）, or the deep tight type, and （c） the composite tight type. For the AD type, gas charging occurs prior to reser- voir densification, accumulating in higher positions under buoyancy-controlled mechanisms with critical controlling factors such as source kitchens （S）, regional overlaying cap rocks （C）, gas reservoirs, （D） and low fluid potential areas （P）. For the DA type, reservoir densification prior to the gas charging period （GCP） leads to accumulation in depres- sions and slopes largely due to hydrocarbon expansive forces without buoyancy, and critical controlling factors are effective source rocks （S）, widely distributed reservoirs （D）, stable tectonic settings （W） and universal densification of reservoirs （L）. The composite type includes features of the AD type and DA type, and before and after reservoir densification period （RDP）, gas charging and accumulation is controlled by early buoyancy and later molecular expansive force respectively. It is widely distributed in anticlinal zones, deep sag areas and slopes, and is con- trolled by source kitchens （S）, reservoirs （D）, cap rocks （C）, stable tectonic settings （W）, low fluid potential areas （P）, and universal reservoir densification （L）. Tight gas resources with great resource potential are widely dis- tributed worldwide, and tight gas in China that presents advantageous reservoir-forming conditions is primarily found in the Ordos, Sichuan, Tarim, Junggar, and Turpan- Hami basins of central-western China. Tight gas has served as the primary impetus for global unconventional natural gas exploration and production under existing technical conditions.

北京地区育龄男性与女性TORCH感染情况回顾分析

目的 回顾分析近2016年7月至2022年12月来我院就诊人群的TORCH感染情况,为本地区优生优育工作提供数据参考。方法 利用酶联免疫吸附实验检测男性和非妊娠期女性血清中TORCH各病原体IgG抗体和IgM抗体的阳性情况,对数据进行处理分析。结果 进行TORCH检测的人群,女性人数远高于男性人数;男性和女性之间TOX、RV、CMV和HSV的IgM抗体阳性率均存在差异,男性和女性之间TOX和HSV的所有感染模式存在差异,且所有差异均表现为女性的抗体阳性率高于男性的抗体阳性率;男性RV和CMV的IgM抗体阳性率在不同的季节存在差异,女性的TOX、RV、CMV和HSV-1的IgM抗体阳性率在不同的季节存在差异;男、女性HSV-1和HSV-2抗体IgM阳性率在各季节均存在差异,且男、女性HSV-2的所有感染模式在各个季节中也完全不同;在合并感染中,男、女性的IgG抗体阳性率均以RV+CMV、RV+HSV-1、CMV+HSV-1和RV+CMV+HSV-1为主,且女性的抗体阳性率高于男性,在IgM抗体的阳性率分析中,女性主要以HSV-1+HSV-2为主,男性主要以RV+HSV-1为主,其女性的抗体阳性率也远高于男性。结论 本地区TORCH感染人群主要为女性,TORCH感染的病原体有季节性差异,可针对此特点进行预防;建议增加育龄男性检测TORCH相关项目,可有助于夫妇备孕期感染的预防。

针对混合型分类数据改进的K-modes算法距离公式

传统K-modes算法在分类属性聚类中有着广泛的应用,但是传统算法并不区分有序分类属性与无序分类属性。在区分这两种属性的基础上,提出了一种新的距离公式,并优化了算法流程。基于无序分类属性的距离数值,确定了有序分类属性相邻属性值之间距离数值的合理范围。借助有序分类属性蕴含的顺序关系,构建了有序分类属性的距离公式。计算样本点与质心距离之时,引入了簇内各属性值的比例作为总体距离公式的重要参数。综上,新的距离公式良好地刻画了有序分类属性的距离,并且平衡了两种不同分类属性距离公式之间的差异性。实验结果表明,提出的改进算法和距离公式在UCI真实数据集上比原始K-modes算法及其改进算法均有显著的效果。

基于K-modes的北京传统村落价值评估及其保护策略研究

在中国历史文化发展所形成的文化区划背景下,北京传统村落逐渐显露出典型的地域特征和特殊的文化底蕴,其包含的价值存在于多个维度,对其价值体系、价值构成要素及典型特征的综合判断与研究,是立足地域优势实施“乡村振兴”和实现传统村落文脉传承与传统风貌延续的首要前提。研究基于传统村落价值特征的实地调研,尝试运用K-modes聚类方法,对北京44个传统村落样本进行聚类研究和校核分析,拟划分为综合服务型、生态农业型、休闲度假型、文化遗产型及特色民俗型五种类型,并依据分类型属性及实际发展诉求,提出可持续保护与利用的策略。

Statistical features of aftershock distribution size for moderate and large earthquakes in Chinese mainland

Based on data of earthquake sequences with Ms≥5.0 in Chinese mainland from 1970 to 2004, for different sequence types and different rupture modes of the main shock, the relationship between aftershock distribution size R and the magnitude of the main shock Mo has been studied statistically. Considering the rupture mode of the main shock, we give the quantitative statistical relationships between R and Mo under 95% confidence level for different sequence typos. Qualitatively, lgR, the logarithm of the aftershock distribution size, is positively correlative to the M0, but the data distribution is dispersed. Viewing from different sequence typos, the correlation between R and M0 is very weak for isolated earthquake type （lET） sequence, R distributes in the range from 5 to 60 km; For mainshock-aftershock type （MAT）, lgR is positively correlative to M0; For multiple main shock type （MMT）, the corelation between lgR and M0 is not very obvious when M0≤6.2 and R distributes in the range from 5 to 70 km, while it shows a linear correlation when M0≥6.3. The statistical results also show that the occupational ratios of different sequence types for strike-slip and oblique slip are almost the same. But for dip-slip （mostly are thrust mechanisms）, the ratio of MAT is higher than that of IET and MMT. Comparing with previous results, it indicates that, when M0 is large enough, R is mainly determined by M0 and there is almost no relationship with the rupture mode of the main shock.

Entanglement swapping without joint measurement via a ∧-type atom interacting with bimodal cavity field

This paper proposes a scheme for realizing entanglement swapping in cavity QED. The scheme is based on the resonant interaction of a two-mode cavity field with a ∧-type three-level atom. In contrast with the previously proposed schemes, the present scheme is ascendant, since the fidelity is 1.0 and the joint measurement isn＇t needed. And the scheme is experimentally feasible based on the current cavity QED technique.

智慧教育时代旅游专业生态型教学模式构建

智慧教育背景下,旅游专业教学模式改革已是刻不容缓。生态型教学模式在智慧教育时代具有极大的适切性。构建智慧教育时代旅游专业生态型教学模式,可依托生态学、教育生态学和建构主义为其主要理论基础,以促进师生全面发展和构建和谐师生关系为其教学目标,以人文素养、跨学科知识和行业实境为其教学内容,以智慧教育技术为主要教学手段,以开放、多维、交互的生态空间为其教学环境,以可视化、多元化、过程性评价为主要考核手段。

PERFORMANCE ANALYSIS OF POWER SAVING CLASS OF TYPE Ⅲ IN IEEE 802.16E WITH USER INITIATED TRAFFIC

A novel method for analysing the performance of power saving class of Type III in IEEE 802.16e is proposed, which is applicable to design, maintenance and management for mobile wireless metropolitan area network. Considering the memoryless nature of user initiated packet arrival, a Geom/G/1 queue model with multiple vacations and setup period is built to capture the principle for the power saving class of Type III. By using an embedded Markov chain method and the boundary state variable theory, we obtain the queueing measures such as queueing length, waiting time and busy cycle in steady state. Correspondingly, we derive explicitly the performance measures for the power saving class of Type III in terms of handover ratio, energy saving ratio, and average packet response time. Based on numerical results, we develop a cost function to determine numerically the optimal length of sleep window and the minimal cost with different offered loads.

信息基础设施建设共建共享博弈分析

中国正处于工业经济时代向信息数字经济时代转型的攻坚期,如何更加高效、集约地完成信息基础设施建设和运营,是选择独立建设还是选择共建共享是电信运营商及政府必须面对的现实问题。从模型构建及求解、理论分析、数值模拟等方面,对信息基础设施建设模式进行博弈分析,并以中国移动、中国联通、中国电信三家相互博弈的运营商为例进行分析,探索共建共享模式。研究表明:通过对不同建设成本差异化分类,建立一般均衡模型和静态博弈模型,实现信息基础建设模式的转变,从而在理论上拓展了建设模式的研究。由于共建共享模式能够达到最低的市场价格,并可满足更多的通信服务需求,为此,政府在信息基础设施建设经营模式的宏观调控上,倾向于采用共建共享模式;通过调控成本分摊比例,各运营商自发加入共建共享,共建共享建设方案由最初的政策推动成功地转变为市场导向推动。研究结果为政府部门和电信运营商推动信息基础设施建设共建共享,避免重复建设并提高资源配置效率提供理论依据和支撑;同时,对新时期信息基础设施高效、集约发展,并赋能社会经济发展具有重要的实践意义。