Crossing Limit Cycles of Planar Piecewise Hamiltonian Systems with Linear Centers Separated by Two Parallel Straight Lines

In this paper, we have studied several classes of planar piecewise Hamiltonian systems with three zones separated by two parallel straight lines. Firstly, we give the maximal number of limit cycles in these classes of systems with a center in two zones and without equilibrium points in the other zone (or with a center in one zone and without equilibrium points in the other zones). In addition, we also give examples to illustrate that it can reach the maximal number.

Going straight for the gut:gut-brain axis pathology and treatment of Parkinson's disease

This perspective focuses on the recent literature regarding the role of the gut-brain axis(GBA) in fecal microbiota transplantation(FMT) and stem cell therapy(SCT) in Parkinson's disease(PD).PD is the second most common neurodegenerative disease in the United States,yet therapies remain limited.Current research suggests that the GBA may play a role in the pathogenesis of PD.GBAbased FMT as well as SCT offer promising new avenues for PD treatment.Pro bing the interactions between FMT and SCT with the GBA may reveal novel therapeutics for PD.

Industrial utilization of arsenic-containing gold dressing tailings as pellet prepared by straight grate process

The utilization of arsenic-containing gold dressing tailings is an urgent issue faced by gold production companies worldwide.The thermodynamic analysis results indicate that ferrous arsenate(FeAsO_(4)),pyrite(FeS_(2))and sodium cyanide(NaCN)in the arsenic-containing gold metallurgical tailings can be effectively removed using straight grate process,and the removal of pyrite and sodium cyanide is basically completed during the preheating stage,while the removal of ferrous arsenate requires the roasting stage.The pellets undergo a transformation from magnetite to hematite during the preheating process,and are solidified through micro-crystalline bonding and high-temperature recrystallization of hematite(Fe_(2)O_(3))during the roasting process.Ultimately,pellets with removal rates of 80.77% for arsenic,88.78% for sulfur,and 99.88% for cyanide are obtained,as well as the iron content is 61.1% and the compressive strength is 3071 N,meeting the requirements for blast furnace burden.This study provides an industrially feasible method for treating arsenic-containing gold smelting tailings,benefiting gold production enterprises.

The world's longest straight road

Activity 1.Think about the following questions and write down your answers before reading the text.1.If you had the chance to travel on the longest straight road in the world,what would be the first thing you would do?2.Do you think having such a long straight road has more advantages or disadvan⁃tages?And why?

Related mechanisms and research progress in straight back syndrome

Despite the high prevalence of straight back syndrome(SBS),there is still limited research on this condition,posing challenges for effective diagnosis and treatment.The disease has been known for a long time,but there have been few related studies,which mostly consist of case reports.These studies have not been systematically summarized,making it difficult to meet the current needs of diagnosis and treatment.This article summarized the existing literature and comprehensively reviewed the diagnosis,pathogenesis,treatment,and research status of mitral valve prolapse related to SBS.We specifically emphasized the mechanisms and prognosis of SBS combined with mitral valve prolapse and discussed the latest research progress in this disease.

Document Clustering with Evolutionary Systems through Straight-Line Programs “<i>slp</i>”

In this paper, we show a clustering method supported on evolutionary algorithms with the paradigm of linear genetic programming. “The Straight-Line Programs (slp)”, which uses a data structure which will be useful to represent collections of documents. This data structure can be seen as a linear representation of programs, as well as representations in the form of graphs. It has been used as a theoretical model in Computer Algebra, and our purpose is to reuse it in a completely different context. In this case, we apply it to the field of grouping library collections through evolutionary algorithms. We show its efficiency with experimental data we got from traditional library collections.

Measuring tree stem diameters and straightness with depth-image computer vision

Current techniques of forest inventory rely on manual measurements and are slow and labor intensive.Recent developments in computer vision and depth sensing can produce accurate measurement data at significantly reduced time and labor costs.We developed the ForSense system to measure the diameters of trees at various points along the stem as well as stem straightness.Time use,mean absolute error(MAE),and root mean squared error(RMSE)metrics were used to compare the system against manual methods,and to compare the system against itself(reproducibility).Depth-derived diameter measurements of the stems at the heights of 0.3,1.4,and 2.7 m achieved RMSE of 1.7,1.5,and 2.7 cm,respectively.The ForSense system produced straightness measurement data that was highly correlated with straightness ratings by trained foresters.The ForSense system was also consistent,achieving sub-centimeter diameter difference with subsequent measures and less than 4%difference in straightness value between runs.This method of forest inventory,which is based on depth-image computer vision,is time efficient compared to manual methods and less computationally and technologically intensive compared to Structure-from-Motion(SFM)photogrammetry and ground-based LiDAR or terrestrial laser scanning(TLS).

Straight and twisted Weyl nodal line phonons in Ho2CF2 material

Based on first-principles calculations, symmetry analysis and model construction, we predict that Ho2CF2hosts both straight and twisted Weyl nodal lines in its bulk phonon spectrum. We identify that the top two phonon bands entangle with each other, forming two straight Weyl nodal lines on the K–H and K′–H′paths at the Brillouin zone(BZ) boundary,and six twisted Weyl nodal lines within the BZ. All the Weyl nodal lines along the kz direction and across the entire BZ.The symmetry analysis indicates that these Weyl nodal lines are protected by the PT symmetry and crystal symmetry. The Berry phase and drumhead-like nontrivial surface states are calculated. We also construct a tight-binding model to describe these nodal lines. Our work provides an excellent material platform for exploring the fascinating physics associated with straight and twisted Weyl nodal line phonons.

Development and Performance Evaluation of Catalyst for Productive Ethylene Cracking Feedstock in Selective Hydrocracking of Straight Run Diesel Oil

The upgrading of diesel oil to produce ethylene rich cracking feedstock is an important and promising technical route to reduce the ratio of diesel to gasoline. In the present work, a hydrocracking catalyst suitable for selective hydrocracking of straight run diesel oil to produce high-quality ethylene cracking feedstock at low cost was developed, by optimizing the composition of catalyst support materials, using amorphous silicon aluminum and aluminum oxide with high mesopore content as the main support, and modified Y zeolite with excellent aromatic ring opening selectivity as the acidic component. The catalyst has in-depth characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, N2-low temperature adsorption-desorption, NH3-temperature-programmed desorption, and IR techniques. And its catalytic cracking straight run diesel oil performance was evaluated. The results show that the prepared catalyst has high polycyclic aromatic hydrocarbon ring opening cracking selectivity. However, alkanes retained in diesel distillates can achieve the goal of producing more ethylene cracking feedstocks with low BMCI value under low and moderate pressure conditions. This work may shed significant technical insight for oil refining transformation.

Effect of Specific Verbal Instructions on the Identification of Pain Location during a Passive Straight Leg Raise Test

Musculoskeletal pain is common. Because pain is subjective, objectively describing it is crucial. However, pain assessment may cause distress in patients;therefore, physical therapists (PTs) should conduct these tests quickly and accurately. Simple and clear instructions are recommended for pain assessment. However, few studies have provided evidence to support this hypothesis. Correspondingly, this study aimed to confirm the effectiveness of specific verbal instructions for pain location during five consecutive Passive Straight Leg Raise (PSLR) tests. The 28 asymptomatic participants (age 27.4 ± 9.6 years) who provided informed consent received five consecutive PSLR tests: three without and two with specific verbal instructions to ascertain pain intensity, quality, and location. The participants drew pain locations on a body chart and described the pain intensity and quality after each test. All participants were interviewed regarding the differences they noted in the presence and absence of specific verbal instructions. Each pain location was classified into one of ten areas for statistical analysis. The proportion of participants who changed the pain location was compared between the tests using McNemar’s test, and the kappa coefficient was confirmed for consistency of pain location. There was a significant difference in the proportion of participants who changed their pain location between the second and third tests and from the third to the fourth test (McNemar’s test: p = 0.003). Kappa coefficients had low consistency (κ = 0.28) just after receiving the specific verbal instructions in the fourth test compared to the third test. Consistency improved in the fifth test (κ = 0.57);93% of the participants answered that the pain location had become clearer. This study revealed the effects of specific verbal instructions in identifying pain locations. This detailed information may help PTs provide appropriate treatment and contribute to reducing pain in clinical settings.

直齿锥齿轮系统动态特性参数解域界结构

为研究含间隙直齿锥齿轮系统的幅值跳跃、齿面冲击特性,用谐波平衡法建立系统动力学方程。在频率与间隙、时变刚度、静态综合误差和负载构建的参数平面内用Broyden拟牛顿法和伪弧长延续算法获得系统参数解域界结构,探索系统幅值跳跃、多值解和啮合冲击特性对参数的敏感性。结果表明在系统啮频和轴频主共振区均出现幅值跳跃和多值解现象,在啮频处动态特性更为复杂丰富。小间隙下存在严重的齿面冲击现象,当间隙b>0.98时系统的跳跃与齿面冲击均趋于稳定,系统动态特性对时变啮合刚度不敏感,在高速轻载、较大齿面误差激励下系统的非线性跳跃和齿面冲击均加剧。参数解域界结构为锥齿轮结构设计提供数据支持。

某铜矿选矿厂半自磨系统磨矿负荷分配研究

半自磨+球磨组成的半自磨系统应用广泛,但在应用过程中半自磨机和球磨机负荷不平衡的情况经常出现。结合某铜矿项目,分析了出现负荷不平衡的原因,并通过优化半自磨机入料粒度、增加格子孔孔缝和开孔率、调整半自磨机排矿产品粒度、优化筛缝尺寸、修改直型格子板为弧形格子板、优化破碎后顽石的返回途径等措施,使得半自磨系统新给矿处理量由39 960 t/d提高至42 500 t/d,半自磨功率保持不变,但球磨机运行功率由9 300 kW提升至11 000 kW,半自磨和球磨负荷分配更加合理。通过对不同优化措施的分析和应用,可为解决其他矿山半自磨流程负荷不平衡问题提供借鉴和参考。

长直管道预混气体爆燃波系演化过程研究

为减少工业场所可燃气体生产、运输和储存过程中气体爆炸事故的发生,利用自主搭建的200 mm×200 mm×35 m方形管道和直径为90 mm、长度为10 m的圆形管道,在相同的初始条件下,运用体积分数为9.5%的甲烷/空气预混气体开展爆炸试验,结合压力、火焰传感器对其进行研究。结果表明:2种不同尺度、不同截面的管道中波系演化过程是相同的,点火后火焰由层流向湍流转变,火焰加速导致压缩波相互追赶,最终形成强激波;速度在2种长直管道中的变化趋势相同,都经历了加速—减速—再加速—再减速的过程,方管和圆管中火焰速度最大分别达到69和35.7 m/s,第一道压缩波经壁面反射后压力上升至117%和114%;当反射波与火焰阵面耦合作用时,方管和圆管中火焰速度分别降至73%和93%;体积分数相同的条件下,2种长直管道中第一道压缩波的最大压力值相近,方管中为65.45 kPa,圆管中为67.09 kPa。

采用STRAIGHT模型和深度信念网络的语音转换方法

提出一种将STRAIGHT模型和深度信念网络DBN相结合实现语音转换的方式。首先,通过STRAIGHT模型提取出源说话人和目标说话人的语音频谱参数,用提取的频谱参数分别训练两个DBN得到语音高阶空间的个性特征信息;然后,用人工神经网络ANN将两个具有高阶特征的空间连接并进行特征转换;最后,用基于目标说话人数据训练出的DBN来对转换后的特征信息进行逆处理得到语音频谱参数,并用STRAIGHT模型合成具有目标说话人个性化特征的语音。实验结果表明,采用此种方式获得的语音转换效果要比传统的采用GMM实现语音转换更好,转换后的语音音质和相似度与目标语音更接近。

基于直驶效率数据的机电复合传动系统性能退化评估

目的 基于直驶效率数据,实现机电复合传动系统的性能退化评估。方法 将机电复合传动系统全工况测试周期内的效率云图进行梯度和网格划分,得到各梯度内的网格点数。通过Pick定理,计算各梯度下不规则效率云图的面积,对各梯度效率云图面积求和,即可得到该测试周期内的机电复合传动系统性能退化评估指标。结果 计算了6个全工况测试周期的效率云图面积,结果显示,性能退化评估指标逐渐上升。通过效率云图对比发现,高效区间逐渐增大。从性能退化指标的发展趋势看,目前该传动系统正处于磨合期。结论 该方法能够有效评估机电复合传动系统的性能退化情况。

Robots Get Smarter with Help from Artificial Intelligence

In 2023,residents of 22 homes in New York City agreed to take part in an unusual experiment.For several hours,they performed a variety of common household tasks with an iPhone-outfitted reacher grabber—a tool commonly used for picking up litter and by wheel-chair-bound people to grasp out-of-reach objects(Fig.1)[1,2].As each volunteer conducted simple household activities such as opening and closing doors,picking up bags of trash,turning on toasters,flipping on light switches,and straightening couch cushions,the phones captured video of the grabber’s movements and measured its position and orientation[1].

A self-organization formation configuration based assignment probability and collision detection

The formation control of multiple unmanned aerial vehicles(multi-UAVs)has always been a research hotspot.Based on the straight line trajectory,a multi-UAVs target point assignment algorithm based on the assignment probability is proposed to achieve the shortest overall formation path of multi-UAVs with low complexity and reduce the energy consumption.In order to avoid the collision between UAVs in the formation process,the concept of safety ball is introduced,and the collision detection based on continuous motion of two time slots and the lane occupation detection after motion is proposed to avoid collision between UAVs.Based on the idea of game theory,a method of UAV motion form setting based on the maximization of interests is proposed,including the maximization of self-interest and the maximization of formation interest is proposed,so that multi-UAVs can complete the formation task quickly and reasonably with the linear trajectory assigned in advance.Finally,through simulation verification,the multi-UAVs target assignment algorithm based on the assignment probability proposed in this paper can effectively reduce the total path length,and the UAV motion selection method based on the maximization interests can effectively complete the task formation.

基于STRAIGHT算法的汉语语音morphing方法

提出了一种新的基于STRAIGHT算法的汉语语音morphing方法.通过标注源和目标STRAIGHT频谱上的特征点,并利用线性和对数叠加的方法实现对频谱的morphing;通过插值的方法对基频进行morphing.实验结果表明,morphing后的语音在语义特征不变的情况下,保持了源和目标语音的特征,morphing的结果获得了高质量的合成语音,MOS得分为3.87分.

基于STRAIGHT算法的个性化语音生成方法

介绍了一种基于STRAIGHT语音修改算法的个性化语音的方法。对输入的语音提取基本信息,并进行频谱分析;利用STRAIGHT算法对相关参数进行修改;通过STRAIGHT合成器生成新的个性化的语音。实验结果表明,该方法可以得到高质量的个性化合成语音,MOS得分为4.18分。

Loggerhead Sea Turtles Hand-Reared in Captivity: Isotopic Insights into Their Inherent Dietary Variation

Stable isotope analysis is a widely used method for gathering ecological insights into the diet and feeding habitats of various species. While captive studies often limit lethal sampling and differ from wild conditions, they offer valuable insights into inherent isotopic variations among individuals, which are often assumed to reflect differences between natural populations. In the Sea Turtle Conservation Program, loggerhead turtle hatchlings from different nests were fed. Necropsies were conducted on turtles that died during this period, obtaining bone fragments for analysis. We evaluated the isotopic variation of carbon (δ13C) and nitrogen (δ15N) in bone tissue across six turtle nests (n = 66 samples) and assessed differences in Straight Carapace Length (SCL, n = 71 samples). Using SIBER and nicheROVER in R, we calculated niche width and overlap, while the simmr package determined primary prey assimilation. Despite feeding the hatchlings the same prey, we observed variations in nitrogen isotope assimilation between nests. Nests 4 and 6 had a niche width >1.8‰, indicating consistent consumption frequencies across all prey and >70% niche overlap with other nests. In contrast, nests 1 and 2 showed a narrower niche width (Mugil sp. constituted the primary diet component (>40%) across all groups. This study demonstrates how factors like competition or prey preference can influence the assimilation of diet, even when the source remains constant (inherent variation).