Subjects: Library Science，Information Science >> Information Science submitted time 2021-06-30
Abstract： " ：The literature survey method was used to analyze the role of the Norwegian model in distributing scientific research funds and stimulating scientific research output, as well as our country's problems in the distribution and management of scientific research funds. After a comparative analysis, a research funding distribution model based on the quantitative indicators of the Norwegian model was produced. The thinking applied to China is further introduced in terms of its necessity, possibilities and opportunities.
Peer Review Status:
Awaiting Review
Subjects: Computer Science >> Computer Software submitted time 2021-06-29
Abstract： " Evolution is the driving force behind the evolution of biological intelligence. Learning is the driving force behind human civilization. The combination of evolution and learning can form an entire natural world. Now, reinforcement learning has shown significant effects in many places. However, Currently, researchers in the field of optimization algorithms mainly focus on evolution strategies. And there is very little research on learning. Inspired by these ideas, this paper proposes a new particle swarm optimization algorithm Reinforcement learning based Ensemble particle swarm optimizer (RLEPSO) that combines reinforcement learning. The algorithm uses reinforcement learning for pre-training in the design phase to automatically find a more effective combination of parameters for the algorithm to run better and Complete optimization tasks faster. Besides, this algorithm integrates two robust particle swarm variants. And it sets the weight parameters for different algorithms to better adapt to the solution requirements of a variety of different optimization problems, which significantly improves the robustness of the algorithm. RLEPSO makes a certain number of sub-swarms to increase the probability of finding the global optimum and increasing the diversity of particle swarms. This proposed RLEPSO is evaluated on an optimization test functions benchmark set (CEC2013) with 28 functions and compared with other eight particle swarm optimization variants, including three state-of-the-art optimization algorithms. The results show that RLEPSO has better performance and outperforms all compared algorithms.
Peer Review Status:Awaiting Review
Subjects: Psychology >> Social Psychology submitted time 2021-06-28
Abstract： [Objective] The main purpose of this article is to explore the psychological mechanism of the formation and maintenance of collective memory. [Methods] The psychological mechanism of the formation of collective memory was systematically discussed by epidemiological research methods. [Results] This paper systematically explains the psychological mechanisms of social contagion, retrieval-induced forgetting, shared reality and network convergence in the formation of collective memory. this paper also explains the psychological principle of the validity of collective memory. [Limitations] The research on the validity of cultural memory is insufficient, and it is not sensitive enough to the memory changes caused by media technology changes. [Conclusions] Some achievements have been made in the research of collective memory psychology, but we still need to broaden our horizons and actively promote localization research.
Peer Review Status:Awaiting Review
Subjects: Psychology >> Management Psychology submitted time 2021-06-28
Abstract： Most previous studies have explored the effect of employees' usage of social media from a single perspective and resulted in inconsistent findings. In addition, some studies ignored the possible interactions among different characteristics of social media usage, leading to an incomplete understanding of social media. Therefore, this study attempts to examine two characteristics of social media usage, integrate the two paths of resource buffer and resource gain, and explore the influence mechanism of social media usage on employees' job performance. Specifically, based on the job demands-resources theory, social media has an impact on an organization as a job resource. From the perspective of resource gain path, employees can obtain information about their work through social media to improve their working ability; In addition, the increase in interactive communication through social media deepens mutual understanding and enhances trust. From the perspective of resource buffer path, social media provides employees with a wealth of professional and personal resources. These resources help employees cope with the demands of the workplace, such as distractions and conflicts. Therefore, from the two paths, we assume that work state and interpersonal relationships can act as parallel multiple mediations between social media usage and job performance, respectively. Using a “leader-subordinate” pairing survey, 487 questionnaires were distributed in enterprises in Shanghai and Henan, and 369 valid questionnaires were collected. We found that work-based and social-based social media usage both affect job performance through work engagement. Additionally, the social-based social media usage also affects job performance through relationship conflict mediation. Interaction effect tests further suggest that work-based and social-based social media usage are mutual substitutions for influencing work performance through work engagement. This study has three main contributions to the literature. First, this study investigates the influencing mechanisms of different types of social media usage. Second, the study draws on the job demands-resources theory to explain the impact of social media usage on job performance, enhancing our understanding of reasons we use social media. Finally, the study highlights the substitution between different types of social media usage, offering clarification on the internal mechanism between social media usage and job performance.
Peer Review Status:Awaiting Review
Subjects: Physics >> Geophysics, Astronomy, and Astrophysics submitted time 2021-06-26
Abstract： In this paper we introduced a parameter n to characterize the variation of the speed of light between different inertial systems. In order to satisfy the well-known fundamental principle and not violate some reliable experiments’ results, we should impose some necessary constraints on n. Firstly and importantly, the introduction of n should be in agree with the following three principles: (1)we can define the time in the whole space with a prescribed clock synchronization, (2)the time-space is uniform and the space is isotropic and (3)all the inertial systems are equivalent, which are the inheritance of the special relativity (SR). With some constraints on n, we construct a general coordinate transformation to meet the symmetry of inertial systems. In recent years, many theories have shown the interest in the breakdown of the Lorentz invariance at ultrahigh energy scale, such as the quantum gravity, which imply that the energy of particle has a limited value (called the “Planck energy”) rather than be infinite derived from the Lorentz model. So we construct an expression for n to characterize the violation of Lorentz model. And further, by comparing with the well-known rainbow model, we found that the "maximum energy" derived in our paper is somewhat related to the "maximum energy" assumed in the rainbow model." "
Peer Review Status:Awaiting Review
Subjects: Biology >> Biochemistry Subjects: Medicine, Pharmacy >> Clinical Medicine submitted time 2021-06-25
Abstract： "
Peer Review Status:Awaiting Review
Subjects: Geosciences >> Geology submitted time 2021-06-24
Abstract： Previous studies have concluded that a Trans-Tethyan oceanic subduction zone existed prior collision of India-Eurasian plates, between which the ocean lacked intervening continental slivers. In contrast, we present first geological evidence of Early Cretaceous shortening and Late Jurassic alkali magmatism constraining that the Longzi block, an extensive (>450 km E-W by ca. 130 km N-S) tract of the NE Himalaya is such a continental sliver. The Longzi block records overturned south-vergent folds in Triassic to Lower Cretaceous strata intruded by 136-123 Ma mafic, dioritic, and dacite dikes, constraining Early Cretaceous shortening. The shortening demonstrates the NE Himalayan locating in a compressional setting, rather than an extensional Indian passive continental margin at that time. Triassic strata of NW Australian affinity and Late Jurassic rocks sourced from north India record pre-rifting history. Rifting evidence includes 152.8 Ma alkali intrusive rocks, a Late Jurassic unconformity, and rapid changes in sediment thickness and apparent water depth of deposition recorded in Upper Jurassic strata. The rifting event is coeval with 152-155 Ma oceanic crust in the NE Indian Ocean and a Late Jurassic submarine escarpment with 1200 m of sediments offshore of NW Australia. These data may reflect rifting of the westernmost Argoland continent in NE Himalaya from East Gondwana, followed by collision with a N-dipping Trans-Tethyan intra-oceanic subduction zone in the Early Cretaceous, long before terminal continent-continent collision. The Mesozoic rifting-collision in the Himalayan region unambiguously presents archipelagic paleogeography in eastern Neotethyan, which underwent Cenozoic two-stage Indian-Eurasian collisional processes."
Peer Review Status:Awaiting Review
Subjects: Psychology >> Developmental Psychology submitted time 2021-06-23
Abstract： With the aging situation in China accelerating continuously, learning how to maintain physical and mental health in old age and promote successful aging has become the focus of researchers. As the study on this topic progresses, more and more researchers are realizing that aging is not only a biological decline but also the result of an altered psycho-social structure in the form of aging self-stereotypes. As a prerequisite central process by which aging stereotypes influence individual psychological behaviors and physiological constructions, aging self-stereotypes increase the likelihood that individuals will activate stereotypes of the group to which they belong or identify and engage in stereotype-related behaviors, thereby directly influencing their expectations, goals, and behaviors regarding self-development. Previous research has shown that the “possible future selves” facilitate processes related to the stereotypical self-conceptualization of old age. The “possible future selves” often derive from various areas of the older person’s experiences. As the family gradually becomes the most important place for older adults to socialize, the experiences of emotional support and interaction from family members are likely to influence the expectations of older adults on their “possible future selves” and the internalization of stereotypes as they grow older. However, few studies have focused systematically on the effects of older adults’ affective involvement from family members on aging self-stereotypes. There is also a lack of exploration regarding the dynamic trajectory of the relationship between family affective involvement and aging self-stereotypes in a longitudinal framework. Thus, the present study sought to examine the developmental trajectories of family affective involvement and aging self-stereotypes in older adults and the causal relationship between the two. In this study, a sample of 257 older adults aged over 55 was followed up for one year. The participants were asked to anonymously complete questionnaires. They were assured by the researchers that the study would be conducted purely for research purposes and that participation was voluntary. Latent growth modeling and cross-lagged analysis were used to examine older adults’ initial level of and growth in family affective involvement and aging self-stereotypes, respectively, as well as predict family affective involvement on aging self-stereotypes. Latent growth modeling showed that older adults’ perceptions of affective involvement from family members decreased linearly during the follow-up period while aging self-stereotypes increased linearly. In addition, the initial level of family affective involvement significantly predicted the initial level of and growth in aging self-stereotypes among older adults. Specifically, the lower the initial level of perceived affective involvement of family members, the higher the initial level of aging self-stereotypes in old age. Older adults’ lower initial levels of affective involvement from family members also predicted more rapid growth in aging self-stereotyping. Finally, the rate of decrease in family affective involvement predicted the increases of aging self-stereotypes over time, that is, a steeper decline in the family affective involvement of older adults predicted a steeper increase of aging self-stereotypes. Similarly, cross-lagged analysis showed that family affective involvement negatively predicted aging self-stereotypes after six months. Our findings suggest that developmental trajectories of aging self-stereotypes in older adults are influenced by changes in family affective involvement. This study expands the existing research on family affective involvement and aging self-stereotypes. A better understanding of the causal effects of older adults’ affective involvement from family members on aging self-stereotypes can also help ameliorate intervention programs designed to reduce the internalization of aging stereotypes and improve negative aging self-stereotypes.
Peer Review Status:Awaiting Review
Subjects: Psychology >> Educational Psychology submitted time 2021-06-22
Abstract： Students’ externalizing problem behaviors negatively impact on the current and future development of themselves, classmates and teachers. Managing students’ externalizing problems is a great challenge for teachers. Previous studies in a Western educational environment and experience of excellent domestic head teachers indicate that head teachers can effectively reduce students’ externalizing problem behaviors by adopting negotiation management strategies and building positive teacher-student relationships. Most of the existing studies emphasize the influence of teachers’ negotiation management behavior and the teacher-student relationship on students’ externalizing problem behaviors. However, conversely, the transactional model suggests that students’ externalizing problem behaviors may also affect teachers’ negotiation management behavior and the teacher-student relationship. The present study aims to explore the reciprocal relationships between head teachers’ negotiation management behavior and teacher-student relationship and primary school students’ externalizing problem behaviors from grades four to six in China. The questionnaire on head teachers’ negotiation management behavior, and the strengths and difficulties questionnaire, and the student perception of affective relationship scale was used for measurement were administered to 1407 students from grades four to six at three different periods in one school year. All the measures were reliable and valid. SPSS 20.0 and Mplus 7.4 were used to analyze the data. A cross-lagged model was used to investigate the reciprocal relationship among the head teachers’ negotiation management behavior, the teacher-student relationship, and primary school students’ externalizing problem behaviors. The results reflected that, after controlling for covariates, simultaneous correlation, and auto-regression of variables, head teachers’ negotiation management behavior drove the positive interaction cycle. The head teachers’ negotiation management behavior at Time 1 reduced the students’ externalizing problem behavior, improved the intimacy of the teacher-student relationship, and decreased the conflicts of the teacher-student relationship at Time 2, which further affected the head teachers’ negotiation management behavior, the teacher-student relationship, and the students’ externalizing problem behaviors at Time 3. The students’ externalizing problem behaviors drove the negative interaction cycle. The students’ externalizing problem behaviors at Time 1 reduced the head teachers’ negotiation management behavior, decreased the intimacy of the teacher-student relationship, and increased the conflicts of the teacher-student relationship at Time 2, which further affected the students’ externalizing problem behaviors, the teacher-student relationship, and the head teacher’s negotiation management behavior at Time 3. These observations deepen the understanding of the complex reciprocal relationships between head teachers’ negotiation management behavior and teacher-student relationship and primary school students’ externalizing problem behaviors from grade four to six in China. Additionally, the findings have important implications for preventing and intervening in students’ externalizing problem behaviors. The results reflect that the head teachers need to be aware of the negative “driver” role of students’ externalizing problem behaviors, and consciously use the positive “driver” role of negotiation management behavior to break the negative cycle driven by students’ externalizing problem behaviors. " " " " "
Subjects: Geosciences >> Geology submitted time 2021-06-22
Abstract： Plate boundary evolution and interpreted paleogeography commonly involve the interaction between oceanic ridges and trenches. Western Junggar and Central-North Tianshan, NW China, have previously been regarded as independent orogens, but this model was challenged by the discovery of their similar tropic-subtropic coral assemblages and of Precambrian and Early Paleozoic clasts transmitted from the Central Tianshan in Early to Middle Paleozoic sediments in SW Junggar, suggesting they had been in contact by then. The presence of Late Silurian-Early Devonian adakitic rocks in northern SW Junggar was explained by slab roll-back, which required an active subducting slab in SW Junggar. However, this model is inconsistent with the cessation of arc magmatism immediately after the adakitic magmatism indicating there was no subduction in SW Junggar at those times. By re-evaluating the relevance of four diagnostic features of modern Californian ridge subduction, we propose a new model to explain the Late Silurian-Early Devonian orogenic framework of NW China in terms of sub-parallel ridge-trench interaction. The transmitted clasts from Central Tianshan in Early Paleozoic sediments in SW Junggar, at the same time as the Late Ordovician and Middle Silurian coral assemblages, and the complementary accretionary complex in SW Junggar and magmatic arc in Central Tianshan, are all contributary evidence for an Early Paleozoic subduction system. This subduction zone was intruded by two 446-380 Ma double magmatic belts: 1. A ridge subduction-generated adakitic gabbro-basalt-andesite-diorite-granite-rhyolite suite that intruded a 504-446 Ma accretionary complex in SW Junggar, and 2. a magmatic arc in Central Tianshan. A buoyant subducting ridge rifted and separated these magmatic belts resulting in the opening of a new 414-325 Ma ocean, which is preserved in OIB- and MORB-type ophiolites in SW Junggar and North Tianshan. These geological and geochemical relationships resemble those generated by oceanic spreading in the modern Gulf of California, which led to separation of magmatic belts in Baja California and mainland Mexico. The new ocean split the Central Tianshan magmatic arc from the Early Paleozoic Mt. Xiemisitai-Barleik-Mayile accretionary complex in SW Junggar, which changed to a new passive continental margin that led to deposition of Devonian shallow marine-terrestrial sediments, and to cessation of magmatism at 379-349 Ma. These features, including the Middle Paleozoic orogenic architecture and the geochemical properties of specific magmatic rocks, indicate the development of a Late Silurian-Early Devonian sub-parallel-to-trench ridge subduction. This model not only interprets phenomena mentioned in the above earlier models, but also reconciles unresolved spatial relationships between Western Junggar and the Tianshan. Subsequent closure of the new ocean and subduction of its ridge in the Late Paleozoic gave rise to the archipelagic framework that we see today in NW China. An analysis of worldwide examples of sub-parallel ridge-trench interaction demonstrates that a ridge can undergo multiple episodes of subduction before a terminal ocean closure. In this context our new tectonic model for the western Junggar and Tianshan regions may provide an improved understanding of the structure and evolution of ridge-subduction events in ancient orogenic belts.
Peer Review Status:Awaiting Review
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. submitted time 2021-06-22
Abstract： Given connected map M=(V,E,F), each node V is assigned a spin, two nodes on each edge interact, the Ising model on map m is obtained.Dual transformation from Ising model, The upper and lower bounds of the critical point K* of the phase transition of Ising model on the self dual map are given:0.2406≤K*≤0.7218, the critical point of phase transition of the three-dimensional self dual Ising model is obtained:K*=0.5269.
Peer Review Status:Awaiting Review
Subjects: Biology >> Zoology submitted time 2021-06-21 Cooperative journals: 《古脊椎动物学报》
Abstract： Choristoderes were an important clade of semi-aquatic predators that occupied Laurasian freshwater ecosystems from the Middle Jurassic to the Miocene. During the Early Cretaceous, the neochoristodere lineage evolved large size and long snouts, converging on the body plan of modern crocodilians. Here, we describe a new longirostrine choristodere, Mengshanosaurus minimus gen. et sp. nov. from the Lower Cretaceous Mengyin Formation of Shandong Province, China. The holotype is the smallest reported neochoristodere individual, with a skull length of only 35 mm. The poorly ossified braincase, along with retention of a fontanel at the frontal-parietal suture, indicates this individual was a juvenile. Phylogenetic analyses recovered Mengshanosaurus as a neochoristodere, a placement supported by the presence of a single narial opening, fusion of the nasals, and expansion of the temporal fenestrae. In the Neochoristodera, Mengshanosaurus is sister to a clade consisting of Ikechosaurus, Tchoiria, Simoedosaurus, and Champsosaurus. It differs from other neochoristoderes in having the lacrimal foramen between the prefrontal and lacrimal, in addition to having large vomerine teeth (exceeding one-third the width of corresponding maxillary teeth). The closely arranged marginal teeth and large vomerine teeth suggest juvenile choristoderes may have fed on invertebrates and insects, similar to juveniles of modern crocodilians. However, the observation that very young neochoristoderes had similar skull proportions and marginal tooth shapes to adults, along with features suggesting a more fully aquatic ecology, suggest that neochoristoderes exhibited less pronounced ontogenetic niche shifts than modern crocodilians.
Subjects: Psychology >> Cognitive Psychology submitted time 2021-06-19
Abstract： Visual working memory (VWM) is a limited-capacity cognitive system that is responsible for temporarily storing up to three or four items, maintaining their availability for current cognitive processing. Although VWM capacity is limited, the limit is not fixed. Factors such as the complexity, statistical regularity, real-world spatial regularity, and perceptual grouping principles of memory objects can modulate this capacity. However, the potential influence of higher-order conceptual regularities, such as categorical relationships among memory objects, remains an open and controversial issue. The effect of object category on VWM capacity, if any, has two possibilities: a mixed-category advantage and a same-category advantage. The first is consistent with the neural resource theory, by which the ability to simultaneously process multiple items is limited by the extent to which those items are represented by nonoverlapping neural representations. The same-category advantage is consistent with a prediction yielded by an ideal-observer analysis of VWM, based on the rate-distortion theory. Although the mixed-category advantage is predicted by the neural resource theory, almost all current supporting evidence solely involves faces. On the other hand, although the same-category advantage is consistent with the ideal-observer prediction, there is still lack of direct evidence to support the generalization of this prediction from low-level to high-level features. Hence, in the present study, we used behavioral and electrophysiological methods to explore this issue. Here, we report two behavioral experiments and one event-related-potentials (ERPs) experiment that assess whether category knowledge affects VWM capacity. The experiments were carried out on 60 undergraduate students. A 2 (memory load: two or four) × 2 (category: same or different) × 2 (posture: high similar or low similar) within-subject design was used in this experiment 1. The results showed that category knowledge modulates the capacity of the VWM and leads to a same-category advantage. In experiment2, we changed the presentation of MIs from simultaneous to successive and replicated the findings from Experiment 1, demonstrating that category knowledge leads to larger memory capacity in the same-category rather than in the different-category condition, even if the MIs are sequentially presented. In Experiment 3, in addition to Cowan’s K, the electrophysiological index CDA was measured to further explore the processing mechanism underlying the same-category advantage. Our electrophysiology results show for the first time that same-category objects can induce a smaller contralateral delay activity (an index of VWM capacity) than different-category objects. The CDA results combined with behavioral results indicated that category knowledge can help compact the representations of same-category objects and therefore enlarge the total information capacity of VWM. In conclusion, our data clearly demonstrate an advantageous same-category effect on the capacity of VWM, which indicates that categorical relationships among objects play an important role in expanding the capacity of VWM by enabling the grouping of same-category objects. This suggests that VWM capacity is not fixed but can be flexible depending on the type of information to be remembered. Moreover, our data also suggest that the ideal-observer prediction can be extended from low-level to high-level features.
Subjects: Astronomy >> Astrophysical processes submitted time 2021-06-18 Cooperative journals: 《天文研究与技术》
Abstract：本文提出，用深度神经网络代替快速傅里叶变换法，求解无碰撞引力N体数值模拟方法PM-Tree中的势能，以提升PM-Tree方法的效率，验证深度学习方法加速无碰撞引力N体数值模拟的可行性。无碰撞引力N体数值模拟对研究星系、暗物质晕以及宇宙大尺度结构的形成和演化都有重要意义。而无碰撞引力N体数值模拟的传统方法在大规模问题上的模拟计算非常耗时，其中常用的PM-Tree方法的主要耗时部分是求解势能（解Poisson方程）。本文提出使用深度神经网络代替传统方法加速求解Poisson方程，多次调整并训练和测试深度神经网络模型结构，最终选用了辅以残差网络局部结构的Encoder-Decoder整体结构。验证了深度神经网络解Poisson方程的计算时间复杂度为；同样数据下进行测试，速度快于快速傅里叶变换方法求解和有限差分法求解；在同等采样率的情况下，精度优于快速傅里叶变换方法求解；并且具有可扩展性。故无碰撞引力N体数值模拟中，用深度神经网络可以提升PM-Tree方法中求解势能的速度，从而有效提升整体模拟速度。
Subjects: Astronomy >> Astrophysical processes submitted time 2021-06-18 Cooperative journals: 《天文研究与技术》
Abstract： 卫星激光测距中，为满足不同距离目标的测距要求，需要调整激光光束发散角。通常利用离焦式扩束系统改变两透镜间距离调整发散角会产生离焦像差，影响激光光束质量和系统测距能力。因此，研究离焦像差对激光光束质量和系统测距能力的影响具有重要意义。首先，分析扩束系统对基模高斯光束的变换作用，得到发散角和离焦量的关系。其次，基于基模高斯光束的传播理论，得到离焦像差对光束能量密度空间分布的影响。最后，对于不同距离的卫星，计算存在离焦像差和无离焦像差时激光测距系统接收的回波光子数。仿真结果表明：发散角和离焦量近似服从线性关系，离焦量变化，发散角变化；离焦像差影响光束的能量密度分布，使光斑弥散；对于不同距离的卫星，在不同角放大率下无离焦像差时测距系统接收到的回波光子数约为存在离焦像差时的2倍，可有效提高系统的测距能力。
Subjects: Astronomy >> Astrophysical processes submitted time 2021-06-18 Cooperative journals: 《天文研究与技术》
Abstract： 射电天文是通过接收和处理无线电波以此研究宇宙天体的一门学科，微波接收机则是射电天文观测的核心接收设备。结合中国科学院新疆天文台南山25米射电望远镜现有K波段制冷接收机及未来Q波段毫米波观测需求，本论文提出一种K波段常温接收机研制，该接收机射频工作频率22-24.2GHz，经混频最终输出3.95-6.15GHz的中频信号，主要用于在K波段开展强度校准方法实践及大气不透明度测量。最终采用冷热负载法测试K波段常温接收机噪声温度为402.2K（理论计算为410.6K），标准噪声源为166.3K也满足设计需求，结合斩波轮校准机械结构，该K波段接收机已经具备开展强度校准及大气不透明度测试功能，相关工作也可为南山25米射电望远镜未来Q波段毫米波观测做技术预研。
Subjects: Astronomy >> Astrophysical processes submitted time 2021-06-18 Cooperative journals: 《天文研究与技术》
Abstract： 位于吉林天文观测基地的280mm全天区可转动光电阵是一台用于空间碎片巡天观测的设备，为了研究该设备光度测量性能，评估其测光精度，选择M67疏散星团这一测光定标区中的测光标准星进行观测。首先，在IRAF中对观测图像进行预处理，之后进行较差测光。接着，提取测光数据并将整晚观测数据进行最小二乘直线拟合，拟合结果给出了主消光系数及相应的系统转换系数，并得到仪器星等至标准星等的转换公式。最后，利用计算得到的均方根误差对该设备的测光精度进行大致的评估。计算结果表明在标准测光夜测量亮度亮于13.8等的星时，280mm全天区可转动光电阵的测光精度可达0.13星等。同时将观测图像与UCAC2星表匹对识别，利用背景恒星中的UCAC2标准星做外符精度的校验，结果与前者基本相同。本设备的测光精度基本满足空间碎片巡天观测的要求。
Subjects: Astronomy >> Astrophysical processes submitted time 2021-06-18 Cooperative journals: 《天文研究与技术》
Abstract：脉冲星搜寻是射电天文学领域的重要研究方向，随着大型射电望远镜的不断建设和发展，采集的数据呈指数级增长，如何及时从快速获取的海量数据中准确识别出脉冲星信号成为当前面临的巨大挑战。本文以LOFAR联合阵列巡天项目的观测数据为例，设计了针对单脉冲信号识别的10个特征变量，进一步研究了XGBoost结合包裹式特征选择法在单脉冲信号识别中的应用，并对比分析了GBDT、AdaBoost、随机森林和BP神经网络等模型对单脉冲信号识别的实验效果。实验结果表明，XGBoost结合包裹式特征选择法在单脉冲信号识别方面更具综合优势，其误分类率最低，同时分类结果的精确率、召回率与F1-score值都最高，平均高出其它模型1到2个百分点。从特征选择上来说，有九个特征被选为最优特征。本研究设计的特征变量和识别方法可为我国开展以FAST探测信号为主的脉冲星搜寻提供方法和技术参考。
Subjects: Astronomy >> Astrophysical processes submitted time 2021-06-18 Cooperative journals: 《天文研究与技术》
Abstract：我们利用Lomb-Scargle periodogram方法和加权小波Z变换(Weight Wavelet Z-transform)方法分析了耀变体CGRaBS J0929+5013和 J2146-1525在15 GHz射电和伽马波段约12年的观测数据。分析结果表明耀变体CGRaBS J0929+5013和J2146-1525在射电波段可能存在准周期振荡信号。它们的准周期分别为1435天(3.93年)和1321天(3.62年)，且置信度均>3(99.7%)；而在伽马波段光变周期性较弱。基于超大质量双黑洞系统中的螺旋喷流模型估算了耀变体CGRaBS J0929+5013和J2146-1525的主黑洞质量的分别为4.3×109和2.7×109。为了探讨射电和伽马波段的光变起源，我们用离散相关函数分别计算了耀变体CGRaBS J0929+5013和J2146-1525射电与伽马波段之间的相关性，发现它们之间没有明显的相关性。这表明它们的辐射可能来自不同的区域。
Subjects: Geosciences >> Geography submitted time 2021-06-17 Cooperative journals: 《干旱区地理》
Abstract： ：土地资源的稀缺性与土地利用的多功能性是土地利用冲突产生的根本原因。土地利用冲 突的产生加剧了经济利益、生态效益与社会效益之间的矛盾。土地利用冲突的研究对于实现国土空间规划中的“多规融合”及“三区三线”的划定都具有重要的意义。在阐释土地利用冲突的概念与类型的基础上，针对冲突研究较为分散的现状特征，分别从研究内容和研究方法上综述了近年来国内外相关研究进展。在研究内容上，分析了土地利用冲突的识别及时空动态研究，归纳了土地利用冲突的主要驱动因素及不同驱动因素下冲突的协调与权衡，总结了冲突研究的应用实践。在研究方法上，评价了参与式调查、博弈论、“压力-状态-响应”模型（Pressure-state-response，PSR模型）及其扩展模型、多目标评价和景观生态风险评价等方法在土地利用冲突研究中的适宜性。未来土地利用冲突研究中，应当完善理论体系、扩展研究方法、重视冲突动态、服务国土空间规划。
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