Interacting topological magnons in a checkerboard ferromagnet

This work is devoted to studying the magnon-magnon interaction effect in a two-dimensional checkerboard ferromagnet with the Dzyaloshinskii-Moriya interaction.Using a first-order Green function method,we analyze the influence of magnon-magnon interaction on the magnon band topology.We find that Chern numbers of two renormalized magnon bands are different above and below the critical temperature,which means that the magnon band gap-closing phenomenon is an indicator for one topological phase transition of the checkerboard ferromagnet.Our results show that the checkerboard ferromagnet possesses two topological phases,and its topological phase can be controlled either via the temperature or the applied magnetic field due to magnon-magnon interactions.Interestingly,it is found that the topological phase transition can occur twice with the increase in the temperature,which is different from the results of the honeycomb ferromagnet.

11种抗菌药物体外联合对耐碳青霉烯类肠杆菌药物敏感性分析

目的观察两药联合对耐碳青霉烯类肠杆菌(CRE)的体外联合药物敏感性,筛选出有效的抗感染治疗方案。方法收集2023年1月至12月青岛市第八人民医院临床标本中分离的非重复CRE60株,胶体金免疫层析法检测碳青霉烯酶型,微量肉汤稀释法测定菌株的最低抑菌浓度(MIC),棋盘法对头孢他啶/阿维巴坦(CZA)联合氨曲南(ATM),黏菌素(COL)分别联合替加环素(TGC)、美罗培南(MEM)、头孢哌酮/舒巴坦(SCF)、阿米卡星(AK)、左氧氟沙星(LEV),TGC分别联合MEM、SCF和AK,MEM分别联合SCF、厄他培南(ETP)进行联合药敏试验,部分抑菌浓度指数(FIC)判定联合效果。结果60株CRE均检出碳青霉烯酶,其中肺炎克雷伯菌碳青霉烯酶(KPC)49株、新德里金属β-内酰胺酶(NDM)10株,亚胺培南酶(IMP)1株。CZA对49株产KPC菌株的MIC均≤8mg/L,全敏感;对11株产NDM、IMP酶菌株的MIC均>128mg/L,全耐药;联合ATM后协同率为100%。MEM+SCF的协同率最高,为63.4%,协同率与相加率之和为96.7%。TGC+AK的协同率与相加率最低,为31.7%。KPC酶型和NDM酶型菌株中,MEM+SCF的协同率与相加率之和最高,分别为100.0%和80.0%,COL+LEV的协同率与相加率之和最低,分别为32.6%和30.0%。11种联合方案均无拮抗作用,对CRE菌株的MIC_(范围)、MIC_(50)和MIC_(90)值与各个单药相比均有不同程度的减低。结论CZA单独或联合ATM对CRE菌株有效。MEM+SCF的协同率与相加率之和最高,可作为临床经验用药参考。

激光雷达与相机联合标定进展研究

针对激光雷达与相机标定精度会极大地影响定位初始化,融合定位算法对标定参数的准确性非常敏感,会严重降低融合定位算法的性能和可靠性等问题,提出一种激光雷达与相机联合标定分类方法:论述激光雷达与相机联合标定领域的最新的研究进展;重点分析和总结基于特征的标定方法、基于运动的标定方法、基于互信息的标定方法和基于深度学习的标定方法的突出研究成果;总结出4种标定方法的开源代码工具集,并对这4种标定方法的特点、标定精度和自动化程度进行分析比较;最后,展望激光雷达与相机联合标定研究的发展趋势。

芦苇方格沙障内部积沙形态演化的野外观测

芦苇方格沙障作为和若铁路重要的工程固沙措施之一,其内部积沙形态的演变对芦苇方格的防沙性能有重要影响。为了解芦苇方格沙障内部真实的积沙状态,依托和若铁路建设工程,采用野外监测的手段对芦苇方格沙障内部积沙形态的演变进行为期6个月的监测。结果显示,芦苇方格沙障的积沙量分布沿着主风的方向向后移动。在风向垂直断面上,芦苇方格沙障边缘的积沙厚度要比中心位置大。整个监测时段内,芦苇方格沙障内部的积沙厚度可以用Rotion Tayor曲面函数来很好地描述,并且曲面沿着主风方向凹陷。芦苇方格沙障的结构参数、风速、风向和风速占比是塑造方格内部复杂积沙形态的主要原因。以上研究结果对野外自然状态下芦苇方格沙障内部积沙演变的认识具有重要意义。

乌兰布和沙漠典型沿黄段格状沙障防风固沙效应

[目的]探究乌兰布和沙漠典型沿黄段机械沙障的固沙效果,为沙区沿黄段的沙障合理配置及应用提供理论支撑和科学参考。[方法]以2 m×2 m规格的纱网沙障、聚乳酸(PLA)沙障、麦草沙障为研究对象,通过测定格状沙障近地表10,20,50,100和200 cm处的风速,同步收集近地表0—50 cm处的风蚀物颗粒,对3种格状沙障在形成稳定障面后的防风固沙效应进行研究。[结果]①纱网沙障、PLA沙障和麦草沙障均有效降低了近地表风速,尤以距地表10 cm高度处最为明显。在10.32 m/s风速下,其防风效能分别达到了49.73%,39.92%和38.33%。②PLA沙障的风速廓线呈现S形曲线特征,3种沙障的粗糙度均较裸沙丘有较大提升。③与裸沙丘相比,3种沙障降低了近地表10 cm处风的扰动度。④纱网沙障、PLA沙障和麦草沙障的输沙率随高度均呈指数关系,固沙效应分别为94.37%,44.80%和53.16%。3种沙障相较于裸沙丘有效抬升了沙粒的平均跃移高度,纱网沙障提升为对照的5.35倍。[结论]结合乌兰布和沙漠沿黄段风沙活动程度及材料获取度,沿岸向流动沙丘垂向上依次为麦草沙障固沙、PLA沙障固沙促生、纱网沙障防风固沙优化配置,可以实现3种格状沙障防风固沙效益的最大发挥。

医院药房口服单剂量调配模式的探索与实践

目的:缩短口服单剂量调配时间,提高工作效率。方法:分析既往单剂量分包模式的不足,从设备、软件、流程等方面改进,包括设计智能棋盘式摆药盘、优化合并备用药槽及使用三备用药槽。比较口服单剂量调配模式改进前后的工作效率。结果:使用智能棋盘式摆药盘后,每条口服医嘱的调配时间从之前的(5.4±0.16)s缩短至(3.5±0.27)s,药师调配速度显著提高(P<0.05)。与改进前的全自动摆药模式相较,改进后平均每包调配时间缩短了24.72%~56.39%,平均每包调配时长显著短于改进前(P<0.05)。与人工摆药模式相较,改进前的全自动摆药模式调配药师从3名缩减至2名,每日人均调配医嘱条数提高至2848.90±153.21,显著高于人工摆药模式(P<0.05),工作效率提升了114.82%;改进后的全自动摆药模式每日人均调配医嘱条数提高至3671.90±56.48,显著高于人工摆药模式(P<0.05),效率提升了176.87%。结论:通过对我院既往单剂量调配模式的改进,工作效率显著提高。

耐碳青霉烯类鲍曼不动杆菌联合药敏试验研究

目的了解耐碳青霉烯类鲍曼不动杆菌(CRAB)的分布特征和耐药状况,评价以黏菌素(COL)为基础,分别与头孢哌酮/舒巴坦(SCF)、替加环素(TGC)、亚胺培南(IPM)、美罗培南(MEM)、阿米卡星(AK)和左氧氟沙星(LEV)联合的体外抗菌效果,为临床抗感染治疗提供参考。方法收集2022年我院75株非重复分离的CRAB菌株,用WHONET 5.6软件分析其临床分布和耐药情况。从中筛选25株,采用微量肉汤稀释法测定各药物单独及联合时的最低抑菌浓度(MIC),用棋盘法抑菌试验计算部分抑菌浓度指数(FIC)判定联合效应。结果2022年我院共分离鲍曼不动杆菌145株,其中CRAB 75株,检出率51.7%。CRAB在>70岁老年患者中检出率最高(40.0%),主要来源于血液(41.3%)和痰液(37.3%)标本,ICU是主要分离科室。75株CRAB对5种抗菌药物哌拉西林(PRL)、哌拉西林/他唑巴坦(TZP)、头孢曲松(CRO)、IPM和MEM均100%耐药;对3种药物氨苄西林/舒巴坦(SAM)、头孢吡肟(FEP)和复方磺胺甲噁唑(SXT)的耐药率均>95%;对LEV、SCF、AK、TGC和COL的耐药率分别为86.7%、82.7%、77.4%、2.4%和0.0%。25株CRAB的联合药敏试验显示,COL分别与SCF和TGC的协同率最高(92%和80%),协同率与相加率之和均为100%;COL与IPM、MEM、AK、LEV联合的协同率依次为64%、72%、56%和48%,均无拮抗作用。结论CRAB呈高度耐药,老年和ICU患者是高危人群。COL与SCF联合具有最佳协同作用,COL与LEV联合效果最差,值得临床参考。

R^n上的基于Checkerboard格点的不可分双正交小波

研究了一类基于Checkerboard格点的不可分双正交小波,并证明了其尺度函数逼近阶与光滑性的上界.在此基础上提出了此类小波的构造算法.理论分析表明,使用该算法构造的小波具有很好的对称性、光滑性以及对多维信号采样的视觉优势.此外该算法能够构造具有任意给定消失矩的小波,并且其小波滤波器具有有理系数,这在多维信号处理中具有重要意义.实例分析也验证了构造算法的有效性和上述结论.

基于点密度插值的拓扑优化密度过滤方法研究

在基于密度描述的拓扑优化方法中,棋盘格式和灰度单元等数值不稳定问题严重影响着优化构型的可制造性和实用性.为了解决这些问题,提出了一种改进的密度过滤方法.该方法首先将正方形单元中心点处密度作为设计变量,并利用点插值方法获取设计域内光滑连续的材料密度分布.然后,将单元平均密度作为过滤后的单元物理密度用于结构刚度计算.因此,改进的密度过滤仍是一种线性过滤方法,仅需在经典密度过滤基础上进行简单修改.本文方法的核心在于利用了Voronoi图的最邻近原则,该原则使得目标单元中心处的点密度对该单元内任意点的密度插值权重最大.进一步地,通过在点插值权重函数中引入一个优化参数,达到控制灰度单元比例和确保收敛稳定性的目的.与Heaviside映射过滤不同,该优化参数并不会增加优化问题的非凸性,导致优化求解的收敛性变差.同时,改进的密度过滤天然具有保体积特性,有效避免了类似Heaviside映射过滤中迭代振荡现象的发生.最小柔顺化问题的算例结果表明,改进的密度过滤通过优化参数的改变,既可避免棋盘格式,又能获得接近理想的0~1分布的优化结果.而且,相较于Heaviside映射过滤,其在求解过程中具有更好的鲁棒性及优化效率.

棋盘格艺术在服饰设计中的运用与创新探析

文章对棋盘格艺术在服饰设计中的运用与创新进行了探析。首先介绍了棋盘格艺术的历史渊源,探讨其特点。其次,重点关注了棋盘格艺术在服饰设计中的运用,包括在服饰图案设计中的表现形式、面料和纹理选择上的应用,以及在服饰款式设计中的创新。然后,探讨了棋盘格艺术与服饰设计的融合与创新,并着重介绍了棋盘格的色彩创新、流线形态设计和材质结构创新。

Checkerboard法对ε-聚赖氨酸和壳聚糖抑菌作用的研究

该研究以大肠杆菌和金黄色葡萄球菌为指示菌,探究ε-聚赖氨酸和壳聚糖复配溶液的抑菌效果。结果表明:6μg/mLε-聚赖氨酸和100μg/mL壳聚糖复配溶液对大肠杆菌的抑制作用最佳;16μg/mLε-聚赖氨酸和100μg/mL壳聚糖复配溶液对金黄色葡萄球菌的抑制作用最佳。Checkerboard法表明壳聚糖和ε-聚赖氨酸抑菌作用具有叠加效应。ε-聚赖氨酸与壳聚糖复配溶液处理能够使细菌出现蛋白质泄漏现象。

Automatic three-dimensional reconstruction based on four-view stereo vision using checkerboard pattern

An automatic three-dimensional(3D) reconstruction method based on four-view stereo vision using checkerboard pattern is presented. Mismatches easily exist in traditional binocular stereo matching due to the repeatable or similar features of binocular images. In order to reduce the probability of mismatching and improve the measure precision, a four-camera measurement system which can add extra matching constraints and offer multiple measurements is applied in this work. Moreover, a series of different checkerboard patterns are projected onto the object to obtain dense feature points and remove mismatched points. Finally, the 3D model is generated by performing Delaunay triangulation and texture mapping on the point cloud obtained by four-view matching. This method was tested on the 3D reconstruction of a terracotta soldier sculpture and the Buddhas in the Mogao Grottoes. Their point clouds without mismatched points were obtained and less processing time was consumed in most cases relative to binocular matching. These good reconstructed models show the effectiveness of the method.

Sand-fixing characteristics of Carex brunnescens and its application with straw checkerboard technique in restoration of degraded alpine meadows

Carex brunnescens（Pers.）, a typical clonal species, is considered to be the only herb found to date that can develop on sand dunes in Maqu alpine region of northwestern China. However, the characteristics that C. brunnescens resists to harsh alpine environment have not been documented. In this study, we conducted a field investigation to determine the morphological, reproductive, and sand-fixing characteristics of C. brunnescens. Concomitantly, we transplanted the belowground rhizomes of C. brunnescens to sand dunes and compared the abilities to restore degraded alpine meadows among sand dunes that had no further treatment（SD＋N）, sand dunes that had straw checkerboard technique but no transplanted rhizomes of C. brunnescens（SD＋SCT）, and sand dunes that had both SCT and transplanted rhizomes of C. brunnescens（SD＋SCT＋P）. We found that belowground vertical rhizomes and horizontal rhizomes（including branching rhizomes and main rhizomes） of C. brunnescens were highly developed and that population reproduction was dominated by horizontal rhizomes. C. brunnescens exhibited a significant sand-fixation effect under following conditions： population density was 145–156 ramets/m^2, vegetation cover was 31.2%–39.3%, total length of belowground rhizomes was 11,223 cm/m^2, total length of belowground first-order roots was 9161–10,524 cm/m^2, fresh weight of aboveground part was 198.5–212.6 g/m^2, and fresh weight of belowground part was 578.8–612.4 g/m^2. It should be particularly noted that SD＋SCT＋P treatment（sand dunes that had both straw checkerboard technique and transplanted rhizomes of C. brunnescens） was the best and SD＋N（sand dunes that had no further treatment） was the worst in terms of following biotic indicators： total number of reproductive ramets, total number of belowground rhizomes, and fresh weight of aboveground and belowground parts of C. brunnescens, contents of soil organic carbon, available nitrogen, microbial biomass carbon, and microbial biomass nitrogen. It implies that applying SCT in sand dunes and transplanting belowground rhizomes to sand dunes with SCT could improve both soil fertility and growth of C. brunnescens. These results suggest that the SCT-promoted high reproductive abilities of belowground rhizomes of C. brunnescens can successfully facilitate the establishment of ramets and can thus be an effective strategy to restore degraded vegetation in Maqu alpine region of northwestern China.

A new technique for high precision sub-regional camera calibration based on checkerboard pattern

Camera calibration is critical in computer vision measurement system, affecting the accuracy of the whole system. Many camera calibration methods have been proposed, but they cannot consider precision and operation complexity at the same time. In this paper, a new technique is proposed to calibrate camera. Firstly, the global calibration method is described in de-tail. It requires the camera to observe a checkerboard pattern shown at a few different orientations. The checkerboard corners are obtained by Harris algorithm. With direct linear transformation and non-linear optimal algorithm, the global calibration pa-rameters are obtained. Then, a sub-regional method is proposed. Those corners are divided into two groups, middle corners and edge corners, which are used to calibrate the corresponding area to get two sets of calibration parameters. Finally, some experimental images are used to test the proposed method. Experimental results demonstrate that the average projection error of sub-region method is decreased at least 16% compared with the global calibration method. The proposed technique is simple and accurate. It is suitable for the industrial computer vision measurement.

Hubbard model on an anisotropic checkerboard lattice at finite temperatures: Magnetic and metal–insulator transitions

We study magnetic and Mott transitions of the Hubbard model on the geometrically frustrated anisotropic checkerboard lattice at half filling using cellular dynamical mean-field theory. Phase diagrams over a wide area of the parameter space are obtained by varying the interparticle interaction strength, geometric frustration strength, and temperature. Our results show that frustration and thermal fluctuations play a competing role against the interactions and in general favor a metallic phase without antiferromagnetic order. Due to their interplay, the system exhibits competition between antiferromagnetic insulator, antiferromagnetic metal, paramagnetic insulator, and paramagnetic metal phases in the intermediateinteraction regime. In the strong-interaction limit, which reduces to the Heisenberg model, our result is consistent with previous studies.

Dynamics analysis on transverse cutting mechanism of straw checkerboard paving robot

The transverse cutting mechanism of the checkerboard paving robot, which directly affects the robot＇s operation, is regarded as the most important part in a transverse pavement system This research aims at designing a new system which is appropriate for desert wofidng en- vironments and finishing cutting the rope of straw. In this paper, computer emulating technology is applied, and with three-dimensional modeling by Pro/ENGINEER software, can observe whether or not interference exists. Also, the speed and displacement parameters of the main parts of the cutting system are given by the dynamic emulation by Automatic Dynamic Analysis of Mechanical System （ADAMS）, which theoretically assures the feasibility and appropriateness of the cutting mechanisrn~ Finally, results of the experinaent shows that the cutting mechanism can cut the straw strand as designed.

Bose-Hubbard Model in Checkerboard Superlattices with a Magnetic Field

In this paper we investigate classical and quantum phase transitions of Bose-Hubbard model in checkerboard superlattices with a magnetic field at the mean-field level. By analyzing stability of normal state phase boundaries are obtained analytically for zero and finite temperature in a unified theoretical frame and easily extended to the situation without the magnetic field. All results illustrate that the introduction of the magnetic field enhances the stability of normal state and Mort insulator. In addition we also note that the critical hopping term presents an oscillating behavior inversely following the upper boundary of Hofstadter butterfly.

Hofstadter's Butterfly and Phase Transition of Checkerboard Superconducting Network in a Magnetic Field

We study the magnetic effect of the checkerboard superconducting wire network. Based on the de Gennes- Alexader theory, we obtain difference equations for superconducting order parameter in the wire network. Through solving these difference equations, we obtain the eigenvalues, linked to the coherence length, as a function of magnetic field. The diagram of eigenvalues shows a fractal structure, being so-called Hofstadter＇s butterfly. We also calculate and discuss the dependence of the transition temperature of the checkerboard superconducting wire network on the applied magnetic field, which is related to up-edge of the Hofstadter＇s butterfly spectrum.

Wideband radar cross-section reduction using plasma-based checkerboard metasurface

For stealth technology,in order to overcome the limitations of thin-layer plasma for electromagnetic waves attenuation and further broaden the radar cross-section(RCS)reduction(RCSR)band of the metasurface,the plasma-based checkerboard metasurface composed of plasma and checkerboard metasurface is investigated to achieve better RCSR.We designed a checkerboard metasurface which can achieve abnormal reflection to reduce RCS and whose-10d B RCSR bandwidth is from 8.1 to 14.5 GHz,the RCSR principle of it lies in the backscattering cancellation,which depends on the phase difference of artificial magnetic conductor(AMC)units.The designed plasma-based checkerboard metasurface is a thin composite structure,including a checkerboard metasurface,a plasma layer,and an air gap which is between them.Full wave simulations confirm that the plasma-based checkerboard metasurface’s–10 dB RCS reduction bandwidth and RCS reduction amplitude,are both increased under different polarized waves compared with the only single plasma or the only metasurface.We also introduced the reason and mechanism of the interaction between plasma and the checkerboard metasurface to improve the RCSR effect in detail.As plasma-based checkerboard metasurface does not need the plasma to be too thick for plasma stealth,its application in practical scenarios is easier to implement.

基于控制点排序的透视变换原木截面测量方法

木材被盗案件中,需要先找到被盗的可疑树木,然后和留在地面的基部伐桩进行比对,确认可疑树木为被盗树木。为了辅助公安机关判断可疑木材是否为被盗木材,需要精确测量被盗木材的基部伐桩和可疑木材的截面大小等特征。首先对留在地面的基部伐桩进行拍照,并对找到的可疑木材截面进行拍照,然后比对2个截面的相似性,从而判断可疑木材是否属于被盗木材。由于被盗木材一般数量庞大,摄像机拍照存在畸变,拍照的姿态、角度和焦距以及环境光照都对成像有具体影响,因此,提出采用矩形棋盘格和最小二乘透视变换的方法,将所有的棋盘格角点作为控制点,并根据透视变换的直线特征不变性,构建了一种基于Hough变换的控制点排序方法。该方法能够将不同角度、不同姿态拍摄的图像变换到鸟瞰图像,并缩放到原始尺寸,从而进行测量。对于不同角度、不同姿态、不同焦距、不同光照条件下的图像,本研究提出的透视变换方法均可以把特征棋盘格及棋盘格后面的伐桩图像校正到图像的中间位置,得到伐桩的鸟瞰图,精确地复原伐桩的原貌。对校正后的图像采用MATLAB的imtool工具进行测量,测量结果表明,该方法测量误差最大为2.45%,能满足公安机关对可疑木材是否为被盗木材的辅助判断需求。