Research and development of a 0.5-m-long helical superconducting undulator prototype

The helical undulator is in high demand in synchrotron radiation facilities for circular polarization generation.Owing to the higher field strength provided by the superconducting undulator compared to the conventional permanent-magnet undulator,greater research efforts should be directed toward this area.The helical superconducting undulator holds great potential in synchrotron radiation facilities,especially in low-energy storage rings that seek circularly polarized radiation with the highest possible radiation flux.Following the successful development of planar superconducting undulators,the Institute of High Energy Physics conducted research and development for the helical superconducting undulator.A 0.5-m-long Deltatype superconducting undulator prototype was developed and tested.Detailed information on the design,fabrication,and cryogenic testing of the prototype is presented and discussed.

Embodying rather than encoding:Towards developing a source-filter theory for undulation gait generation

Biological undulation enables legless creatures to move naturally,and robustly in various environments.Consequently,many kinds of undulating robots have been developed.However,the fundamental mechanism of biological undulation gait generation has not yet been well explained,which hinders deepening the investigation and optimization of these robots.Towards developing a theory for explaining this biological behavior,which will further guide the design of artificial undulation systems,we propose a hypothesis based on both biological findings and previous robotics studies.To verify the hypothesis,we investigate embodied intelligence of undulation locomotion via a mechanical system.Through experimental study,we observe the phenomenon that undulation gait is a production of the source,which is the torque inputs,and the filter,which is the natural dynamics of the system.We further derive a general mathematical model and conduct morphological computation accordingly.From a simple model to a complicated system,our work explores the principles of undulation gait generation.Our findings significantly simplify the control system design of artificial undulating systems.

Formation Mechanisms of Some Features in Siliceous Upper Cretaceous-Lower Tertiary Beds of Jordan-Undulations, Geodes, Boudinages

Geode, boudinage, and undulation structures are widely distributed in the siliceous beds of the Upper Cretaceous/Tertiary rocks in Jordan. Their formation was attributed to tectonic forces, syngenetic processes, organic disintegration processes, subaquatic gliding, compaction and settlement, and meteoritic impacts. In this work, the structural features in the siliceous beds of Jordan are attributed to an interplay of load and directed pressures, and mineralogical transformation processes (opal-A to opal-CT to quartz), governed by pH changes. Tectonic directed pressure was acting in an ESE-WSW direction and is common in the silicified limestone of Upper Cretaceous.

Performance of the merged APPLE-Knot undulator for soft x-ray beamline in medium energy ring

APPLE-Knot undulator can effectively solve the on-axis heat load problem and is proven to perform well in VUV beamline and soft x-ray beamline in high energy storage ring. However, for soft x-ray beamline in a medium energy ring,whether the APPLE-Knot undulator excels the APPLE undulator is still a question. Here, a merged APPLE-Knot undulator is studied to generate soft x-ray in a medium energy ring. Its advantages and problems are discussed. Though the on-axis heat load of the APPLE-Knot undulator is lower in linear polarization modes compared to the APPLE undulator, its flux is lower. The APPLE-Knot undulator shows no advantage when only fundamental harmonic is needed. However, in circular polarization mode, the APPLE-Knot undulator shows the ability to cover a broader energy range which can remedy the notable shortcoming of the APPLE undulator.

波纹唇鱼染色体核型分析

为了解波纹唇鱼(Cheilinus undulates)的细胞生物学特征,采用植物血凝集素PHA、秋水仙素腹腔注射和空气干燥制片法以头肾组织为材料,对波纹唇鱼的染色体核型进行了研究。结果表明,波纹唇鱼具有染色体48条,核型公式为2n=48=6m+42t,NF=54,未发现随体、次溢痕及性染色体,其核型符合典型的高位类群鱼类核型特征。

极小长高比腔体内混合流体Undulation行波对流

通过二维流体力学基本方程组模拟了具有较强Soret效应(分离比ψ=-0.47)的混合流体在极小长高比(Γ=4)腔体内的Rayleigh-Benard对流运动.研究了极小长高比行波对流的动力学特性,得到了稳定的Undulation行波存在的r值范围,给出了稳定后的Undulation行波摆动周期Tp的变化规律,分析了极小长高比行波对流的r依赖性及稳定性.首次发现极小长高比Γ=4时,与长高比Γ=12和Γ=8时相比,在腔体两端的滚动生成和消失的现象不再出现.讨论了长高比对Undulation行波向行波过渡的影响.

中等长高比腔体内的混合流体Undulation行进波

通过二维流体力学基本方程组模拟了具有较强Soret效应(分离比ψ=-0.47)的混合流体在中等长高比(Γ=12)腔体内的Rayleigh-Benard对流运动。研究了不同瑞利数情况下腔体内出现的各种行进波状态,详细地探讨了Undulation行进波(UTW)的特性、时空结构及稳定性。

野生波纹唇鱼Cheilinus undulates营养成分分析与评价

该研究测定了野生波纹唇鱼Cheilinus undulates肌肉的营养成分。结果显示,波纹唇鱼肌肉(鲜样)的水分、粗蛋白、粗脂肪和粗灰分的含量分别为80.97%、18.38%、0.10%和0.49%。肌肉中含有18种氨基酸,总量为15.70%(鲜重),必需氨基酸含量占氨基酸总量的39.37%,必需氨基酸的组成符合FAO/WHO的标准。氨基酸的支/芳值为2.5654,接近正常人的支/芳值;依据氨基酸评分(AAS)结果,第一限制性氨基酸为苏氨酸(Thr),第二限制性氨基酸为色氨酸(Trp);必需氨基酸指数(EAAI)为68.46;4种鲜味氨基酸(SAA)的总量为31.85%。脂肪酸中二十碳五烯酸(EPA)+二十二碳六烯酸(DHA)的含量为21.86%。含有人体所必需的钠、钾、钙、镁、铁、铜、锌等元素,表明波纹唇鱼具有较高的营养价值。

具有强SORET效应的混合流体Undulation行进波对流斑图

本文通过流体力学基本方程组的数值模拟,探讨了具有强Soret效应(分离比ψ=-0.6)的混合流体Un-dulation行进波对流斑图的动力学特性。在相对瑞利数r<6.436时,首次发现一种没有源缺陷的左右相对传播的CPW(Counter propagating waves)状态向行进波状态的过渡形式。在r=6.436—10.8的范围内,发现了两种不同结构的Undulation行进波对流斑图。当6.436<r<10时,出现了腔体内的平均波数在时间上变化且局部波数或当地波数在空间和时间上连续变化的Undulation行进波对流斑图。当r=10—10.8时,出现了腔体内的平均波数在时间上保持为常数而局部波数或当地波数在空间和时间上连续变化的Undulation行进波斑图。在两种状态下,Undulation行进波的摆动周期随瑞利数r增大而减小,它的对流振幅和Nusselt数随瑞利数r增大而增加。在Undulation行进波斑图形成以前,存在以中心为对称的Undulation行进波斑图,它的存活时间依赖于r。当r增加到11.0时,Undulation行进波过渡到定常对流状态。

波纹巴非蛤小分子肽在水剂化妆品中的稳定性

试验考察了含量、空气暴露时长、光照、pH、化妆品常用防腐剂等因素对波纹巴非蛤（Paphi0 Undu-Zctte）小分子肽抗氧化活性的影响，并研究了其在化妆品体系中的稳定性。结果表明．波纹巴非蛤小分子肽在含量为0．2％～1．0％（m／V）时对自由基的清除能力随含量增大而增强，当含量达到1．0％时，羟自由基清除率为66％，超氧阴离子自由基清除率为70％，且24h空气暴露对自由基清除能力无影响：波纹巴非蛤小分子肽的光和pH稳定性良好；常用化妆品防腐剂对其稳定性基本无影响，但避免加入量过大。波纹巴非蛤小分子肽作为抗氧化活性物质适于与大部分水剂化妆品原料进行配伍．

Brucellosis: Pathophysiology and new promising treatments with medicinal plants and natural antioxidants

Brucellosis is an old, infectious and common zoonosis whose causative agents are Gramnegative bacteria from the Brucella genus. Brucellosis is transmitted through direct contactwith infected animals or using unpasteurized dairy products of goats, pigs, camels, sheep,buffalo and cows. Brucellosis is still the most common zoonosis in the world, with mostof cases occurring in developing countries. Today, an approach to traditional medicine andmedicinal plants, especially with regards to the repeated recommendations of the World HealthOrganization, is a necessity. One-third of chemical drugs are produced by using plants andthere is a high potential to produce more drugs from plants. Medicinal plants are helpful inthe management of various conditions, especially bacterial diseases. Although there is notenough scientific evidence regarding the clinical effectiveness of herbal drugs for the treatmentof brucellosis, there is strong evidence on the antimicrobial effects of herbal drugs to preventinfection. Therefore, this article seeks to describe the antibacterial effects of some plantderived essential oils or extracts, so that they can serve as promising choices to develop newanti-Brucella medications, as suitable alternatives to conventional antibiotics for brucellosis, asmuch as possible, taking into account the benefits of these herbal drugs.

Direct pre-stack depth migration on rugged topography

Engineering seismic exploration aims at shallow imaging which is confused by statics if the surface is uneven. Direct pre-stack depth migration （DPDM） is based on accurate elevations of sources and receivers, by which static correction is completely abandoned before migration and surely the imaging quality is remarkably improved. To obtain some artificial shot gathers, high-order staggered-grid finite-difference （FD） method is adapted to model acoustic wave propagation. Since the shot gathers are always disturbed by regular interferences, the statics still must be applied to supporting the interference elimination by apparent velocity filtering method. Then all the shot gathers should be removed back to their original positions by reverse statics. Finally, they are migrated by pre-stack reverse-time depth migration and imaged. The numerical experiments show that the DPDM can ideally avoid the mistakes caused by statics and increase imaging precision.

Seroprevalence of brucellosis among exposed agro-pastoral communities in southern Saudi Arabia

Objective: To investigate the prevalence and risk factors of brucellosis in human and animal’s communities in southern Saudi Arabia.Methods: A cross-sectional sero-epidemiological study was conducted in Aseer and Jazan, Saudi Arabia(October 2017-October 2018). Human serum samples(n=339) were initially screened for Brucella antibodies and positive samples were further titrated for Brucella antibodies by immunocapture assay(titer of ≥1:320 as positive). Animal samples(n=828) were screened using the Rose Bengal test. Relationship status was dichotomized to measure and predict independent contributions to variations in human using univariate and multivariate stepwise binary logistic regression model. Results: The rate of brucellosis among the 339 human samples in the two regions was 33.9%, and the rate of acute brucellosis was 12.4%. The rate of brucellosis in animals was 4.7%. Human brucellosis among the target groups was higher in northwestern Aseer(53.3%) compared to Southeastern Aseer(25.9%) and Jazan region(20.6%). The disease was more prevalent among non-Saudi nationals(35.2%) compared to Saudis(30.5%). The rate of brucellosis among butchers and shepherds was 37.5% and 37.2%, respectively. The rate of brucellosis was 37.8% in people over 30 years of age. Our univariate analysis showed that residing in Aseer region(OR: 2.60, 95% CI: 1.50-4.40), especially residing in northwestern Aseer region(OR: 4.40, 95% CI: 2.40-7.90), frequent consumption of raw meat(OR: 2.90, 95% CI: 1.50-5.50), shepherds(OR: 2.10, 95% CI: 0.80-5.30), owning sheep(OR: 2.20, 95% CI: 1.10-4.40), daily contact with animals(OR: 2.10, 95% CI: 0.75-5.80), and those > 30-year-old(OR: 1.50, 95% CI: 1.00-2.40) were significantly associated with increased risks of brucellosis. Our multivariate analysis further showed that residing in northwestern Aseer(OR: 9.16, 95% CI: 3.39-24.76) and having sheep(OR: 1.16, 95% CI: 1.00-1.35) were significant and independent risks of brucellosis while residing in agricultural region(OR: 0.28, 95% CI: 0.10-0.78) was a significant and independent protector against brucellosis.Conclusions: The study concluded that residing in northwestern Aseer area and having animals(sheep) are associated with significantly increased risks of brucellosis.

Singularity-free expression of magnetic field of cuboid under undulating terrain

Most of the current computing methods used to determine the magnetic field of a uniformly magnetized cuboid assume that the observation point is located in the upper half space without a source. However, such methods may generate analytical singularities for conditions of undulating terrain. Based on basic geomagnetic field theories, in this study an improved magnetic field expression is derived using an integration method of variable substitution, and all singularity problems for the entire space without a source are discussed and solved. This integration process is simpler than that of previous methods, and final integral results with a more uniform form. AT at all points in the source-flee space can be calculated without requiring coordinate transformation; thus forward modeling is also simplified. Corresponding model tests indicate that the new magnetic field expression is more correct because there is no analytical singularity and can be used with undulating terrain.

Auto-pick first breaks with complex raypaths for undulate surface conditions

First-break picking is the key step in seismic data processing for surveying undulate surfaces, and directly infl uences the precision of near-surface modeling and effects of static corrections. The current first-break auto-picking methods may fail when the signalto-noise ratio（SNR） is low for seismic data in the undulate area, and require labor and time intensive manual picking. This study develops an improved super-virtual interferometry（SVI） method that combines multichannel and multidomain quality control（MMQC） techniques to achieve auto-picked first breaks. The improved SVI method extends the SVI application to enhance the SNR for near-surface scattered waves for the first time, which allows for the SVI method to adapt to first breaks with complex raypaths by linear combination of refractions and near-surface scattered waves. Methods of inverse and multidomain interferometry are developed to effectively enhance the virtual records extracted by the SVI method. The deconvolution filter for waveforms is used to increase resolution and reduce false picks, while the MMQC technique is designed to auto-correct false picks and increase the stability of auto-picking first breaks. The robust technique developed in this study enables stable processing of large 3D seismic datasets. Higher quality results are obtained using the approach presented in this paper to actual field data from the mountain areas in western China, when compared to some commonly used commercial software.

Computational Study on a Squid-Like Underwater Robot with Two Undulating Side Fins

The undulating fin propulsion system is an instance of the bio-inspired propulsion systems. In the current study, the swimming motion of a squid-like robot with two undulating side fins, mimicking those of a Stingray or a Cuttlefish, was investigated through flow computation around the body. We used the finite analytic method for space discretization and Euler implicit scheme for time discretization along with the PISO algorithm for velocity pressure coupling. A body-fitted moving grid was generated using the Poisson equation at each time step. Based on the computed results, we discussed the features of the flow field and hydrodynamic forces acting on the body and fin. A simple relationship among the fin＇s principal dimensions was established. Numerical computation was done for various aspect ratios, fin angles and frequencies in order to validate the proposed relationship among principal dimensions. Subsequently, the relationship was examined base on the distribution of pressure difference between upper and lower surfaces and the distribution of the thrust force. In efficiency calculations, the undulating fins showed promising results. Finally, for the fin, the open characteristics from computed data showed satisfactory conformity with the experimental results.

Computational Research on Modular Undulating Fin for Biorobotic Underwater Propulsor

Biomimetic design employs the principles of nature to solve engineering problems. Such designs which are hoped to be quick, efficient, robust, and versatile, have taken advantage of optimization via natural selection. In the present research, an environment-friendly propulsion system mimicking undulating fins of stingray was built. A non-conventional method was considered to model the flexibility of the fins of stingray. A two-degree-of-freedom mechanism comprised of several linkages was designed and constructed to mimic the actual flexible fin, The driving linkages were used to form a mechanical fin consisting of several fin segments, which are able tO produce undulations, similar to those produced by the actual fins. Owing to the modularity of the design of the mechanical fin, various undulating patterns can be realized. Some qualitative observations, obtained by experiments, predicted that the thrusts produced by the mechanical fin are different among various undulating patterns. To fully understand this experimental phenomenon is very important for better performance and energy saving for our biorobotic underwater propulsion system. Here, four basic undulating patterns of the mechanical fin were performed using two-dimensional unsteady computational fluid dynamics （CFD） method. An unstructured, grid-based, unsteady Navier-Stokes solver with automatic adaptive re-meshing was used to compute the unsteady flow around the fin through twenty complete cycles. The pressure distribution on fin surface was computed and integrated to provide fin forces which were decomposed into rift and thrust. The pressure force and friction force were also computed throughout the swimming cycle. Finally, vortex contour maps of these four basic fin undulating patterns were displayed and compared.

Identification of Odor Volatile Compounds and Deodorization ofPaphia undulata Enzymatic Hydrolysate

Unfavorable fishy odour is an inevitable problem in aquatic products. In the present study, headspace solid-phase mi- croextraction gas chromatography mass spectrometry （HS-SPME-GC-MS） analysis of volatiles from untreated samples and three deodorized samples （under the optimal conditions） ofPaphia undulata enzymatic hydrolysate revealed that the compounds contrib- uting to the distinctive odor were 1-octen-3-ol, n-hexanal, n-heptanal, 2,4-heptadienal, and 2,4-decadienal, whereas n-pentanal, n-octanal, n-octanol, benzaldehyde, 2-ethylfuran and 2-pentylfuran were the main contributors to the aromatic flavor. The deodoriz- ing effects of activated carbon （AC） adsorption, yeast extract （YE） masking and tea polyphenol （TP） treatment on a P. undulata en- zymatic hydrolysate were investigated using orthogonal experiments with sensory evaluation as the index. The following optimized deodorization conditions were obtained： AC adsorption （35 mg mL-1, 80℃, 40 rain）, YE masking （7 mgmL l, 45 ℃, 30 min） and TP treatment （0.4mgmL-l, 40℃, 50min）. AC adsorption effectively removed off-flavor volatile aldehydes and ketones. YE masking modified the odor profile by increasing the relative contents of aromatic compounds and decreasing the relative contents of aldehydes and ketones. The TP treatment was not effective in reducing the odor score, but it significantly reduced the relative content of alde- hydes while increasing that of alkanes. It is also notable that TP effectively suppressed trimethylamine （TMA） formation in a P. un- dulate hydrolysate solution for a period of 72 h.

Parametric Research of Experiments on a Carangiform Robotic Fish

In this paper, a carangiform robotic fish with 4-DoF （degree of freedom） tail has been developed. The robotic fish has capability of swimming under two modes that are radio control and autonomous swimming. Experiments were conducted to investigate the influences of characteristic parameters including the frequency, the amplitude, the wave length, the phase difference and the coefficient on forward velocity. The experimental results shown that the swimming performance of the robotic fish is affected mostly by the characteristic parameters observed.

Understanding the Rayleigh instability in humping phenomenon during laser powder bed fusion process

The periodic undulation of a molten track’s height profile in laser-based powder bed fusion of metals(PBF-LB/M)is a commonly observed phenomena that can cause defects and building failure during the manufacturing process.However a quantitative analysis of such instabilities has not been fully established and so here we used Rayleigh–Plateau theory to determine the stability of a single molten track in PBF-LB/M and tested it with various processing conditions by changing laser power and beam shape.The analysis discovered that normalized enthalpy,which relates to energy input density,determines whether a molten track is initially unstable and if so,the growth rate for the instability.Additionally,whether the growth rate ultimately yields significant undulation depends on the melt duration,estimated by dwell time in our experiment.