Existence of horseshoe maps in voltage-mode controlled buck converters

In this paper, chaos in a voltage-mode controlled buck converter is studied. The existence of chaos is proven theoretically in this system. The proof consists of showing that the dynamics of the system is semiconjugate to that of a one-sided shift map, which implies positive entropy of the system and hence chaotic behaviour. The essential tool is the horseshoe hypotheses proposed by Kennedy and Yorke, which will be reviewed prior to the discussion of the main finding.

Effect of Intertidal Elevation at Tsuyazaki Cove,Fukuoka,Japan on Survival Rate of Horseshoe Crab Tachypleus tridentatus Eggs

Physical factors affecting the survival of Tachypleus tridentatus eggs were investigated by translocating their eggs between the high intertidal zone and the low intertidal zone of a known spawning site.The mean egg survival rates per day were highest in the mid intertidal zone(45.1%±25.4%)and the lowest in the low intertidal zone(13.3%±27.6%).Differences in the elevation,air exposure time,and water content of the spawning ground were significant factors determining the egg survival rates.Excessive or insufficient air exposure time resulted in inadequate water content at higher and lower intertidal zones and could reduce egg survival.On the other hand,moderate saturation and dehydration were repeated with each tidal movement in the mid intertidal zone.This dynamic is considered as one of the crucial factors for the survival of eggs and is considered optimal for spawning.Therefore,the protection of the mid intertidal zone is imperative for maximizing the egg survival rate in Tsuyazaki Cove where almost all suitable nesting sites have disappeared due to coastal development.By protecting these optimal sites for spawning and recovering other optimal sites on suitable beaches,a positive contribution can be made to future management and conservation.The study also suggests that translocating eggs from marginal to optimal spawning sites might be a recovery strategy for this globally endangered species.

Topological horseshoe in nonlinear Bloch system

This paper demonstrates rigorous chaotic dynamics in nonlinear Bloch system by virtue of topological horseshoe and numerical method. It considers a properly chosen cross section and the corresponding Poincare map, and shows the existence of horseshoe in the Poincare map. In this way, a rigorous verification of chaos in the nonlinear Bloch system is presented.

Horseshoe and entropy in a fractional-order unified system

This paper studies chaotic dynamics in a fractional-order unified system by means of topological horseshoe theory and numerical computation. First it finds four quadrilaterals in a carefully-chosen Poincare section, then shows that the corresponding map is semiconjugate to a shift map with four symbols. By estimating the topological entropy of the map and the original time-continuous system, it provides a computer assisted verification on existence of chaos in this system, which is much more convincible than the common method of Lyapunov exponents. This new method can potentially be used in rigorous studies of chaos in such a kind of system. This paper may be a start for proving a given fractional-order differential equation to be chaotic.

Comparison of the Macrozoobenthic Community and Sedimentary Environment with and Without Horseshoe Crab Presence in the Crocodile Island Intertidal Zone,Xiamen,China

In order to compare the macrozoobenthic community and sedimentary environment with and without the presence of horseshoe crabs,the benthic macrofauna,sediment grain size,chromium(Cr),cobalt(Co),nickel(Ni),polycyclic aromatic hydrocarbon(PAHs),organic carbon and nitrogen were seasonally investigated at site A(with horseshoe crab presence),sites B and C(without horseshoe crab presence)in the Crocodile Island intertidal zone in Xiamen from June 2018 to July 2019.The results showed that most of the community parameters of benthic macrofauna,population parameters of common benthic macrofauna and environmental parameters were significantly different at the sites with horseshoe crab versus non-horseshoe crab sites.A two-way ANOVA test showed that the densities of Ceratonereis erythraeensis and Sigambra hanaokai had significant site variation.Cluster and nonmetric multi-dimensional scaling(NMDS)analysis showed the community composition of benthic macrofauna was significantly different among the three sampling sites over four seasons.The mean sand content at site A(64.32%)was higher than those at site B(36.01%)and site C(18.86%).Conversely,the mean contents of silt,clay,Cr,Co,Ni,organic carbon,organic nitrogen,phenanthrene,and pyrene at site A were lower than those at site B and site C.These observations are consistent with the expected preferences of horseshoe crabs to live in areas with 60%sand content,which is associated with abundant and edible clamworms in the Crocodile Island intertidal zone,Xiamen.

Topological horseshoe analysis and field-programmable gate array implementation of a fractional-order four-wing chaotic attractor

We present a fractional-order three-dimensional chaotic system, which can generate four-wing chaotic attractor. Dy- namics of the fractional-order system is investigated by numerical simulations. To rigorously verify the chaos properties of this system, the existence of horseshoe in the four-wing attractor is presented. Firstly, a Poincar6 section is selected properly, and a first-return Poincar6 map is established. Then, a one-dimensional tensile horseshoe is discovered, which verifies the chaos existence of the system in mathematical view. Finally, the fractional-order chaotic attractor is imple- mented physically with a field-programmable gate array （FPGA） chip, which is useful in further engineering applications of information encryption and secure communications.

Circulation characteristics of horseshoe vortex in scour region around circular piers

This paper presents an experimental investigation of the circulation of the horseshoe vortex system within the equilibrium scour hole at a circular pier, with the data measured by an acoustic Doppler velocimeter （ADV）. Velocity vector plots and vorticity contours of the flow field on the upstream plane of symmetry （y = 0 cm） and on the planes ：e3 cm away from the plane of symmetry Cv = ~3 cm） are presented. The vorticity and circulation of the horseshoe vortices were determined using the forward difference technique and Stokes theorem, respectively. The results show that the magnitudes of circulations are similar on the planes y = 3 cm and y = -3 cm, which are less than those on the plane y = 0 cm. The circulation decreases with the increase of flow shallowness, and increases with the densimetric Froude number. It also increases with the pier Reynolds number at a constant densimetric Froude number, or at a constant flow shallowness. The relative vortex strength （dimensionless circulation） decreases with the increase of the pier Reynolds number. Some empirical equations are proposed based on the results. The predicted circulation values with these equations match the measured data, which indicates that these equations can be used to estimate the circulation in future studies.

Horseshoe方法及其在BIM技术研究中的应用

梳理了BIM及BIM技术的内涵;通过研究BIM技术的研究现状,指出在BIM技术研究中,一个统一、规范、科学、被研究者普遍接受的研究方法的重要性;介绍了Horseshoe方法及其在BIM技术研究中的作用。

基于Horseshoe+先验的惩罚置信区域变量选择方法

针对高维稀疏线性回归问题,相关变量的数量远远少于不相关变量.相关变量的变量选择问题对于传统的频率论正则化方法是一大挑战.现有的贝叶斯惩罚置信区域法通过将模型拟合与变量选择分离,在联合后验置信区域内搜索最稀疏解,从而得到稀疏模型解.且该方法在高维变量选择效果上优于常用的变量选择方法.在此基础上,针对高维稀疏模型,将原方法中依赖的共轭正态先验替换成针对“稀疏信号勘测问题”提出的Horseshoe+先验,利用Horseshoe+先验对小系数“重”压缩与大系数几乎零压缩的理论特性,实现对稀疏回归系数的稳健估计.通过数据仿真模拟不同稀疏程度下的高维稀疏线性回归,并将基于Horseshoe+先验的惩罚置信区域法分别与基于正态先验以及Laplace先验的该方法进行比较,结果表明基于Horseshoe+先验的惩罚置信区域法在高维稀疏线性回归问题具有更好的变量选择效果与预测效果.

High Microplastic Contamination in Juvenile Tri-Spine Horseshoe Crabs:A Baseline Study of Nursery Habitats in Northern Beibu Gulf,China

Microplastics(MPs)are ubiquitous in marine sedimentary environments.Their occurrence in horseshoe crabs and interactions with the sedimentary environment has not been determined.In this study,MPs,mostly microfibers,were found in all extracted gastrointestinal tract(GIT)samples of the juvenile Tachypleus tridentatus from the northern Beibu Gulf,China.The MP concentrations(4–53 items ind-1)were higher than those in most marine benthic invertebrates(<15 items ind-1)reported in Chinese waters,despite their generally low level in habitat sediments(9–1818 items kg-1).The correlation between the juveniles and sediments was not evident,but the abundance in juvenile horseshoe crab GITs decreased with ages.The findings were relevant to the life-history characteristics of the species,typically with limited dispersal capability and their spending nine years or longer time living in mangrove wetlands during low tides,with apparent ontogenetic changes in their diets.These baseline data enable a better understanding of MP availability in benthic macroinvertebrates,and the ecological risks present in the ecosystems.

Interaction of a submerged horseshoe vortex with a free surface

In this paper a submerged horseshoe vortex under a free surface is discussed and the algebraic expression of the wave elevation is obtained. From this expression, some characteristics of the ship wave are described. There exists a smooth region nearθ=0°, but when the uniform stream passes the other singularities （source, sink, doublet, etc.） there is no smooth region. The mechanism of synthetic aperture radar （SAR） images of the narrow ship wakes is also explained.

Hyperstatic reaction method for calculations of tunnels with horseshoe-shaped cross-section under the impact of earthquakes

Tunnels are now an integral part of the infrastructure in major cities around the world. For many reasons, these tunnels have horseshoe-shaped cross-sections with round top and flat bottom. This paper presents some improvements to the use of the Hyperstatic Reaction Method-HRM for analysing tunnels with horseshoe-shaped cross-sections when these tunnels operate under the influence of earthquakes, particularly in cases when the tunnel lining is a continuous lining. The analysis used parameters of a tunnel from the Hanoi metro system, as well as parameters of the strongest earthquake that may occur in the central Hanoi area in the improved HRM and 2 D numerical methods using the ABAQUS software. On the basis of the results obtained, the paper gives conclusions about the HRM methodology when it is used to calculate tunnels that have horseshoe cross-sections operating under the influence of earthquakes.

Retroperitoneal vs transperitoneal laparoscopic lithotripsy of 20-40 mm renal stones within horseshoe kidneys

BACKGROUND Horseshoe kidney(HK)with renal stones is challenging for urologists.Although both retroperitoneal and transperitoneal laparoscopic approaches have been reported in some case reports,the therapeutic outcome of retroperitoneal compared with transperitoneal laparoscopic lithotripsy is unknown.AIM To assess the efficacy of laparoscopic lithotripsy for renal stones in patients with HK.METHODS This was a retrospective study of 12 patients with HK and a limited number(n≤3)of 20-40 mm renal stones treated with either retroperitoneal or transperitoneal laparoscopic lithotripsy(June 2012 to May 2019).The perioperative data of both groups were compared including operation time,estimated blood loss,postoperative fasting time,perioperative complications and stone-free rate(SFR).RESULTS No significant difference was observed for age,gender,preoperative symptoms,body mass index,preoperative infection,hydronephrosis degree,largest stone diameter,stone number and isthmus thickness.The mean postoperative fasting time of the patients in the retroperitoneal group and the transperitoneal group was 1.29±0.49 and 2.40±0.89 d,respectively(P=0.019).There was no significant difference in operation time(194.29±102.48 min vs 151.40±39.54 min,P=0.399),estimated blood loss(48.57±31.85 m L vs 72.00±41.47 m L,P=0.292)and length of hospital stay(12.14±2.61 d vs 12.40±3.21 d,P=0.881)between the retroperitoneal and transperitoneal groups.All patients in both groups had a complete SFR and postoperative renal function was within the normal range.The change in estimated glomerular filtration rate(e GFR)from the preoperative stage to postoperative day 1 in the retroperitoneal group and the transperitoneal group was-3.86±0.69 and-2.20±2.17 m L/(min·1.73 m2),respectively(P=0.176).From the preoperative stage to the 3-mo follow-up,the absolute change in e GFR values for patients in the retroperitoneal group and the transperitoneal group was-3.29±1.11 and-2.40±2.07 m L/(min·1.73 m2),respectively(P=0.581).CONCLUSION Both retroperitoneal and transperitoneal laparoscopic lithotripsy seem to be safe and effective for HK patients with a limited number of 20-40 mm renal stones.

Bilateral hematoma after tubeless percutaneous nephrolithotomy for unilateral horseshoe kidney stones:A case report

BACKGROUND Bilateral perirenal hematoma is rarely reported in endoscopic management of horseshoe kidney stones,and there are few studies reporting the formation of bilateral hematoma following tubeless percutaneous nephrolithotomy(PCNL)for unilateral horseshoe kidney calculi.CASE SUMMARY A 32-year-old man was admitted to our hospital because of repeated intermittent hematuria for 10 years.Plain abdominal computed tomography(CT)scan revealed calculi in the horseshoe kidney;the largest being 2 cm in diameter.Tubeless PCNL was performed to remove the stones.Three days after the operation,the patient was discharged in a stable situation.Three days after discharge,the patient presented to our emergency department because of right low back pain and vomiting.Emergent CT scan revealed subcapsular and perirenal hematocele and exudates in both kidneys.Ultrasound-guided puncture and drainage of perirenal effusion were performed.After the temperature stabilized,the patient received low-pressure injection of urokinase 100000 U for 3 d.His routine blood indexes and the renal function returned to normal in 3 wk.CT re-examination 3 mo after lithotripsy showed that the subcapsular and perirenal hematoma and exudates in both kidneys were significantly absorbed as compared with those before.The patient was followed up for 1 year,during which no flank pain or hematuria recurred.CONCLUSION This is the first case report on the formation of bilateral hematoma following tubeless PCNL for unilateral horseshoe kidney calculi.

Heminephrectomy for a large renal mass in a horseshoe kidney: A case report outlining a robotic assisted laparoscopic approach

With an incidence of 1/500,a horseshoe kidney is not uncommon.Tumours discovered in horseshoe kidney however are quite rare,and prove difficult to surgically manage due to complex vascular anatomy.With variable surgical approaches previously described,only a select few robot-assisted cases have been reported.This case describes one such robot-assisted laparoscopic heminephrectomy,with the use of indocyanine green and an endovascular stapler to successfully demarcate ischemia and achieve hemostasis intraoperatively.No complications were encountered,and pathology revealed a pT1bN0 clear cell renal cell carcinoma with negative surgical margins,demonstrating the feasibility of our approach.

SMALE HORSESHOES AND CHAOS IN DISCRETIZED PERTURBED NLS SYSTEMS （Ⅰ）-POINCARE MAP

The existence of Smale horseshoes for a certain discretized perturbed nonlinear Schroedinger （NLS） equations was established by using n-dimensional versions of the Conley-Moser conditions. As a result, the discretized perturbed NLS system is shown to possess an invadant set A on which the dynamics is topologically conjugate to a shift on four symbols.

SMALE HORSESHOES AND CHAOS IN DISCRETIZED PERTURBED NLS SYSTEMS(Ⅰ)—POINCAR MAP

The existence of Smale horseshoes for a certain discretized perturbed nonlinear Schroedinger （NLS） equations was established by using n-dimensional versions of the Conley-Moser conditions. As a result, the discretized perturbed NLS system is shown to possess an invariant set A on which the dynamics is topologically conjugate to a shift on four symbols.

Comparative evaluation of urolithiasis management options in patients with horseshoe kidney:A systematic review and meta-analysis

Background:Horseshoe kidney is a rare congenital anomaly commonly complicated by urolithiasis.Extracorporeal shockwave lithotripsy(ESWL),ureteroscopy(URS),and percutaneous nephrolithotomy(PCNL)are treatment options for horseshoe kidney stones.The aim of this systematic review is to compare the benefits and risks of these management options.Methods:MEDLINE,EMBASE,and Cochrane Library databases were searched from inception to February 2022.A total of 516 nonduplicate studies were screened against the inclusion and exclusion criteria.Studies comparing at least 2 interventions with>10 patients per intervention were included.Results:Nine retrospective observational studies published from 2007 to 2021 with a total of 565 patients were included.Reported mean±SD or mean(range)stone sizes ranged between 17.90±2.43 mm and 27.9±8.6 mm for PCNL,8.4(2-25)mm and 22.3±9.1 mm for URS,and 11.9±2.0 mm and 16.8±4.4 mm for ESWL.There was no difference in single-session and overall stone-free rate(SFR)between PCNL and URS,with a risk ratio of 1.04(95%confidence interval,0.95-1.13;I2=20.63%).Ureteroscopy had better stone clearance than ESWL,with an overall SFR risk ratio of1.38(95%confidence interval,1.04-1.82;I2=0%).There was no statistically significant difference in overall SFR between PCNL and ESWL.Most patients who underwent URS and ESWL experienced Clavien-Dindo(CD)gradeⅠ-Ⅱcomplications.Percutaneous nephrolithotomy was associated with the highest complication rates,including 5 CD gradeⅢand 3 CD gradeⅣcomplications and a mean postoperative hemoglobin drop of 0.47 to 1.83 g/dL.There were no CD grade V complications across all studies.Conclusions:There was no difference in SFR between PCNL and URS.Ureteroscopy was associated with a smaller stone burden and fewer and less severe complications.Ureteroscopy was found to be more effective than ESWL with a higher SFR and comparable safety profile.Further large-scale randomized controlled trials are needed to confirm these findings.

A rare triple concurrence of ureteric calculus and renal cell carcinoma in a horseshoe kidney

Horseshoe kidney is a rare anatomical variant with low clinical morbidity.However,the characteristic shape of horseshoe kidney causes significant anomalies within the vascular and collecting systems.This complicates the diagnosis and management of coexisting pathologies within the kidneys.Here,we report a rare case of concurrent diagnoses of ipsilateral ureteric calculus and renal cell carcinoma within a horseshoe kidney and describe the subsequent management rationale based on the current literature.

A study of the effect of local scour on the flow field near the spur dike

The flow field near a spur dike such as down flow and horseshoe vortex system(HVS)are susceptible to the topographic changes in the local scouring process,resulting in variation of the sediment transport with time.In this study,large eddy simulations with fixed-bed at different scouring stages were conducted to investigate the changes in flow field.The results imply that the bed deformation leads to an increase in flow rate per unit area,which represent the capability of sediment transportation by water,in the scour hole.Moreover,the intensity of turbulent kinetic energy and bimodal motion near the sand bed induced by the HVS were also varied.However,the peak moments between the two sediment transport mechanisms were different.Hence,understanding the complex feedback mechanism between topography and flow field is essential for the local scour problem.