Effect of speed humps on instantaneous traffic emissions in a microscopic model with limited deceleration capacity

As a common transportation facility, speed humps can control the speed of vehicles on special road sections to reduce traffic risks. At the same time, they also cause instantaneous traffic emissions. Based on the classic instantaneous traffic emission model and the limited deceleration capacity microscopic traffic flow model with slow-to-start rules, this paper has investigated the impact of speed humps on traffic flow and the instantaneous emissions of vehicle pollutants in a single lane situation. The numerical simulation results have shown that speed humps have significant effects on traffic flow and traffic emissions. In a free-flow region, the increase of speed humps leads to the continuous rise of CO_(2), NO_(X) and PM emissions. Within some density ranges, one finds that these pollutant emissions can evolve into some higher values under some random seeds. Under other random seeds, they can evolve into some lower values. In a wide moving jam region, the emission values of these pollutants sometimes appear as continuous or intermittent phenomenon. Compared to the refined Na Sch model, the present model has lower instantaneous emissions such as CO_(2), NO_(X) and PM and higher volatile organic components(VOC) emissions. Compared to the limited deceleration capacity model without slow-to-start rules, the present model also has lower instantaneous emissions such as CO_(2), NO_(X) and PM and higher VOC emissions in a wide moving jam region. These results can also be confirmed or explained by the statistical values of vehicle velocity and acceleration.

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.

Suppressing of humping bead using an external magnetic field in high-speed gas metal arc welding

During high-speed gas metal arc welding （GMAW）, the backward flowing molten jet with high momentum in the weld pool is considered to be responsible for the occurrence of humping bead. To suppress humping bead, an electromagnetic device is developed and coupled with the welding system. By adjusting the conditions of external magnetic field, forward electromagnetic force is obtained to reduce the momentum of the backward flow of molten metal in weld pool. Consequently, the humping bead can be suppressed by adjusting the external magnetic field. Bead-on-plate welding experiment was conducted on mild steel plates, and the influence of magnetic flux density on the arc deflection angle and weld bead quality is investigated. It is found that external magnetic field can remarkably adjust the momentum of backward flow jet and significantly improve the quality of weld bead.

Influence of backward flowing molten jet on humping bead formation during high-speed GMA welding

Considering the influence of backward flowing molten jet observed by experiments, a new pool surface deformation formula and droplets heat content model are used to investigate the humping formation mechanism during high-speed gas metal arc （GMA） welding. Three-dimensional geometry of the humping bead is numerically simulated only if some extra force and heat acted at the rear part of weld pool are taken into account in the model. It has proved that both the momentum and heat content of backward flowing molten jet must be appropriately treated to quantitatively analyze the physical mechanism of the humping phenomenon.

Entropy Production Analysis for Hump Characteristics of a Pump Turbine Model

The hump characteristic is one of the main problems for the stable operation of pump turbines in pump mode.However,traditional methods cannot reflect directly the energy dissipation in the hump region.In this paper,3D simulations are carried out using the SST k-ω turbulence model in pump mode under different guide vane openings.The numerical results agree with the experimental data.The entropy production theory is introduced to determine the flow losses in the whole passage,based on the numerical simulation.The variation of entropy production under different guide vane openings is presented.The results show that entropy production appears to be a wave,with peaks under different guide vane openings,which correspond to wave troughs in the external characteristic curves.Entropy production mainly happens in the runner,guide vanes and stay vanes for a pump turbine in pump mode.Finally,entropy production rate distribution in the runner,guide vanes and stay vanes is analyzed for four points under the 18 mm guide vane opening in the hump region.The analysis indicates that the losses of the runner and guide vanes lead to hump characteristics.In addition,the losses mainly occur in the runner inlet near the band and on the suction surface of the blades.In the guide vanes and stay vanes,the losses come from pressure surface of the guide vanes and the wake effects of the vanes.A new insight-entropy production analysis is carried out in this paper in order to find the causes of hump characteristics in a pump turbine,and it could provide some basic theoretical guidance for the loss analysis of hydraulic machinery.

Effect of welding current and speed on occurrence of humping bead in high-speed GMAW

The developed mathematical model of humping formation mechanism in high-speed gas metal arc welding （GMAW） is used to analyze the effects of welding current and welding speed on the occurrence of humping bead. It considers both the momentum and heat content of backward flowing molten jet inside weld pool. Three-dimensional geometry of weld pool, the spacing between two adjacent humps and hump height along humping weld bead are calculated under different levels of welding current and welding speed. It shows that wire feeding rate, power intensity and the moment of backward flowing molten jet are the major factors on humping bead formation.

A method for optimization of time intervals between rolling cuts on sorting humps

Sorting humps are the main technical means providing the breaking- and making-up of freight trains. Automation of sorting process by implementing microprocessor control systems is the main direction ofincreasing hump yard capacity, enhancement of safety in trains breaking-up, improvement of working conditions on hump yards. However, for wider introduction of such systems at the humps, it is necessary to reduce their cost. One of the main tasks of hump control systems is the determination of the optimal cars exit speeds from the retarders. Its solution is significantly complicated because of the uncertainty of cars rolling resistance coefficient, wind velocity and direction, retarder control errors. The paper is aimed at solving the problem of searching for such cars exit speeds from the retarders that provide the longest time intervals between them at the switches. Implementation of this method will make it possible to improve the quality of sorting process as a whole by improving the software of microprocessor control systems for automatic humping, rather than by increasing their technical facilities, which as a result will reduce the cost of their construction and operation. The research results, when solving the problem of searching for cars exit speeds from the retarders, allow us to move from searching for the maximum of a nonlinear non-smooth function of two variables to solution of an equation with one variable, which significantlyaccelerates and simplifies the solution to the problem.

Traffic Calming in Quebec： Speed Humps and Speed Cushions

Speed management is an essential tool in ensuring the improved safety of users of urban roads, particularly vulnerable users. It relies on several measures： awareness campaigns, speed control, as well as the development and operation of the road infrastructure. Municipalities in Quebec are increasingly resorting to the development of traffic calming measures, and are facing numerous questions concerning their installation and their effectiveness. To respond to this need, the ministere des Transports du Quebec （Quebec Department of Transport） has begun publishing a series of fact sheets on a variety of traffic calming measures, including speed humps and speed cushions, raised crosswalks and intersections, neckdowns, centre islands and chicanes. A general fact sheet introduces all of the measures and notably outlines the procedure for pre-implementation analysis. Each fact sheet dedicated to an individual measure outlines the implementation context, advantages and disadvantages, geometric characteristics, effectiveness at reducing speed, and maintenance requirements, including winter maintenance. Two fact sheets are already published： the general fact sheet and the fact sheet on speed humps and speed cushions. The fact sheets as well as examples of measures implemented in municipalities are available on the minist6re＇s web site under Partenaires-Municipalites-Securite routiere.

Hump nosed viper bite in Sri Lanka-descriptive observational study of 1543 cases

Objective:To identify the clinical manifestations of hump nosed viper envenomation and to recognize the available treatment methods to prevent complications.Methods:Descriptive observational study involving a series of 1 543 patients admitted with hump nosed viper bite to 5 major hospitals in Sri Lanka was conducted.Data collection was done consecutively during February 1990 and February 2008.Except Hypnale,identification of the biting snake was made by the corresponding author after visual examination of the dead or live snakes,which were brought to hospital.Results:Sixty seven(4.34%) patients developed systemic effects and two (0.1%) patients died due to effects of envenomation or complications of treatment.Systemic effects varied from coagulopathy,nephropathy to some neurological manifestations.Fifty nine (3.8%) patients had only coagulopathy and they received either,intravenous isotonic saline to ensure adequate urine out put i.e.0.5 mL/kg /hour or 15 mL/kg of fresh frozen plasma(FFP). None of the patients that had coagulopathy developed renal failure.Contamination of the sample by mildly venomous species of Hypnale may have contributed to the low incidence of systemic complications.Conclusions:It is likely that early hydration with normal saline or FFP can prevent acute renal failure.FFP showed a tendency for early correction of coagulopathy.Role of FFP in hump nosed viper envenomation is worth studying in randomized double blind controlled clinical trials.

Positive gate bias stress-induced hump-effect in elevated-metal metal-oxide thin film transistors

Under the action of a positive gate bias stress, a hump in the subthreshold region of the transfer characteristic is observed for the amorphous indium-gallium-zinc oxide thin film transistor, which adopts an elevated-metal metal-oxide structure. As stress time goes by, both the on-state current and the hump shift towards the negative gate-voltage direction. The humps occur at almost the same current levels for devices with different channel widths, which is attributed to the parasitic transistors located at the channel width edges. Therefore, we propose that the positive charges trapped at the back-channel interface cause the negative shift, and the origin of the hump is considered as being due to more positive charges trapped at the edges along the channel width direction. On the other hand, the hump-effect becomes more significant in a short channel device （L=2 μm）. It is proposed that the diffusion of oxygen vacancies takes place from the high concentration source/drain region to the intrinsic channel region.

On Gliding Hump Properties of Matrix Domains

In this note, we establish several results concerning the gliding hump properties of matrix domains. In order to discuss F-WGHP, we introduce the UAK-property and find that this sort of property has close relationship with F-WGHP. In the course of discussing F-WGHP and WGHP of （C0）cn, we discuss the F-WGHP and WGHP of the almost-null sequence space f0.

Hump formation mechanism in gas-jet-assisted keyhole laser welding of HR-2 stainless steel

Gas-jet-assisted keyhole laser welding offers the possibility of a breakthrough in the limitations of penetration depth in laser welding,which currently suffers from equipment restrictions.A gas jet of sufficient intensity to assist the keyhole should be used to obtain suppressed plasma,a deepened keyhole,and increased penetration depth.However,an excessively strong gas jet gives rise to humps.The incident angle of the keyhole-assisted gas jet is 60°,with a nozzle ahead of the laser beam.A series of experiments were carried out with different welding velocities and gas parameters by using HR-2 hydrogen-resistant stainless steel and a slab CO2 continuous-wave laser welding machine.The weld profiles can be categorized into four types,welds of traditional laser welding,welds of enhanced laser welding,undercut welds,and humping welds with increased gas pressure.A high-speed camera was employed in the experiments to monitor the formation of humps under an excessively strong gas jet.The results of analysis show that hump formation can be divided into six stages.Its main driving force is the intense turbulence of gas jet.There are two main reasons for hump formation：premature solidification of the molten pool caused by the large temperature gradient between the front and rear parts of the molten pool,and the emergence of a thin layer liquid bridge with one-directional flow under the enhanced cooling effect of excessively strong gas.

The chest X ray in pulmonary embolism: Westermark sign, Hampton's Hump and Palla's sign. What's the difference?

Pulmonary embolism (PE), with the incidence of about 60 per 100000 annually, can be a life-threatening disease if it is not treated promptly. It has been estimated that some 10% of PE patients die within the first hour of the event. Untreated PE has a mortality of about 30%. PE is a condition that is treatable if suspected and diagnosed early. The chest radiograph is still the first investigation that is ordered in patients presenting with cardiorespiratory symptoms or symptoms suggestive of PE. The CXR is also helpful in identifying or excluding other conditions or diagnoses. Thus, knowing and understanding some of the more specific CXR signs can be useful. We suggest that physicians to be aware of and utilize CXR findings such as Palla's sign, Westermark sign and Hamptons hump to help with the diagnosis of PE and to exclude other conditions that can mimic venous thrombo-embolism. Even if these signs are not common, their presence, even in an unsuspected patient without a high pretest probability of PE, should prompt further investigations such as a D-dimer test, lung scintigraphy or computed tomography pulmonary angiography as required.

The Dual Pair with the Signed-weak Gliding Hump Property

In this paper, we introduce the signed weak gliding hump property in a dual pair with the structure of a system of sections and show that if a dual pair [E, F] has the signed weak gliding hump property, then the β-dual space of E is a weak sequentially complete space if and only if for every n ∈N,(F[n] ,σ(F[n] ,E[n] )) is sequentially complete. Furthermore, we also prove that if [E,F] has the signed weak gliding hump property, then (E,τ(E,E<β> )) is an AK- space.

Parallels between Russell's viper(Daboia russelii) and hump-nosed viper(Hypnak species) bites in the central hills of Sri Lanka amidst the heavy burden of unidentified snake bites

Objective:To describe the epidemiology of snake bite in the region and attempt to compare proven Russell’s viper with hump-nosed viper bites.Methods:All snake bite admissions to the Toxicology Unit of Teaching Hospital Peradeniya over three year from 2006 were included. Results:Of the 776 snakebites,665(86%) were unidentified and non-envenomed.Humpnosed viper and Russell’s viper accounted for 55(7%) and 40(5%) bites respectively,of them, incriminated snakes were found in 36(65%) and 19(48%) cases.The cobra bites-5,krait bites-0. The median ages:Russell’s viper bites-41(range 16-66),hump-nosed viper bites-42(range 15- 75).The gender incidence,time of bite(】58%daytime) were similar.In hump-nosed viper bite; upper limb involved in 13(36%),happened at home garden in 22(61%),none in paddy fields.In Russell’s viper bite;6(33%) occurred in paddy fields.Dry bites were similar at 5%.In humpnosed viper bite:local effects 94%,coagulopathy 3%,acute renal failure 3%and one patient died.In Russell’s viper bite;local effects 84%,coagulopathy 53%,neurotoxicity 21%.Abdominal pain occurred only in Russell’s viper bites 10(53%).Conclusions:Overwhelming numbers of unidentified,non-envenomed snakebites are common in the central hills.Some distinctive differences were observed between Russell’s viper and hump-nosed viper bites.

Infinite Matrix Rings on Spaces with Signed-Weakly Gliding Hump Property

In this paper, several elementary properties of infinite matrix rings on spaces with the singed weakly gliding hump property are obtained.

Can Fresh Frozen Plasma Prevent Acute Kidney Injury after Hump-Nosed Viper Bite?

Hump-nosed viper bite is the commonest venomous snakebite in Sri Lanka. Acute kidney injury (AKI) in association with coagulopathy is an important cause of mortality. Immunomodulating effects of fresh frozen plasma (FFP) could block the nephrotoxic effects of venom;and by replenishing depleted clotting factors resulting from venom induced consumption coagulopathy could offer an additional benefit in offsetting renal injury triggered by haematological disturbances. In a non-randomised observational study carried out from 2005 to 2008 in adults at the National hospital of Sri Lanka, the mean time for resolution of coagulopathy among 42 patients treated with FFP at the inception of coagulopathy was 4.7 hours compared to 18 patients treated with isotonic Saline among whom the mean time for normalisation of coagulopathy was 6.2 hours. None of these 60 patients developed acute renal failure. A separate cohort of 32 patients with coagulopathy after hump-nosed viper bite who had not received FFP during this study period developed acute renal failure and required haemodialysis. In the absence of safe and effective antivenom for hump-nosed viper in Sri Lanka, FFP may be a therapeutic option. FFP if given early to selected patients at inception of coagulopathy may prevent AKI and serve to save lives after hump-nosed viper bites.

How the camel got his hump

现在我来讲第二个故事:骆驼背上的驼峰是怎么长出来的。世界刚诞生的时候,一切的一切都是崭新的,动物们刚刚开始为人干活儿。然而,在荒凉的沙漠中有一头骆驼,它什么活儿也不想干,时不时叫喊几声。它每天吃枯枝、红柳、乳草和荆棘,整日无所事事地闲逛。如果有人跟它说话,它用鼻子'哼'一声就不再言语了。星期一的早晨,马来找它。马的背上驮着鞍子,嘴上戴着嚼子,它对骆驼说:'骆驼啊骆驼,来和我们一起忙碌奔跑吧.'骆驼不屑地'哼'了一声。于是马走了,把这件事告诉了人。狗来找它。狗的嘴里叼着一根手杖,对路驼说:'骆驼啊骆驼,来和我们一起送取物品吧.'

How the Camel Got His Hump

Now this is the next tale,and it tellshow the Camel got his big hump^1.In the beginning of years,when theworld was so new and all,and the Animalswere just beginning to work for Man,therewas a Camel,and he lived in the middle of aHowling Desert because he did not want towork;and besides,he was a Howler himself.So he ate sticks and thorns^2 and tamarisks^3and milkweed and prickles^4,~*most scruciating idle^5;and when anybody spoke

基于自动提钩的驼峰溜放部分纵断面设计优化研究

相比人工提钩,自动提钩技术具有更快的响应速度、更精确的控制能力,能够适应更高的推峰速度,可以提升驼峰的解体作业效率。而更高的推峰速度意味着更大的车组初始动能、更短的车组溜放间隔时间,同时也对驼峰溜放部分纵断面提出了新的要求。为研究自动提钩技术对驼峰溜放部分纵断面的影响,本文以推峰速度最大、累计加权溜放时间最小、优化区域高度最低为优化目标,以坡段数量、坡度、变坡点坐标为决策变量,以变坡点位置、分路道岔最大允许入口速度、优化区域末端最小速度等为约束条件,构建基于自动提钩的驼峰溜放部分纵断面设计多目标优化模型,并设计求解算法。仿真计算结果显示,与既有方法相比,本文提出的优化模型中的纵断面方案,推峰速度提高9.5%,累计加权溜放时间减少6.0%,优化区域高度降低4.6%,驼峰总体作业效率提升7.6%,平均制动能耗降低约151 kJ/辆。研究内容可为自动提钩技术的驼峰纵断面改造提供理论依据。