Horizontal Step Research Articles

Stepped chute energy dissipation structure downstream of a low-level river crossing for embankment protection

A low-level river crossing is an economic means of providing access for lower-order roads during high-frequency flood events. Conventionally, culverts are employed to enable the flow to traverse the road, albeit with allowance for overtopping. This overtopping flow from the approach roads, however, possesses the potential to cause erosion of the downstream embankment, thereby jeopardising the foundational integrity of the structure. A physical modelling study was undertaken to investigate the hydraulic performance of stepped chutes in terms of flow patterns, air-water flow properties, and energy dissipation. Various types of stepped chutes were investigated, namely horizontal steps with a chute wall, horizontal steps without a chute wall but with riprap placed directly downstream of each chute, step-inclined steps (backward sloping), steps with pooled cascades, and steps with baffle blocks. Notably, chutes with horizontal steps were the most efficient configuration in terms of relative energy dissipation. Furthermore, this research culminated in the formulation of a new regression formula to establish a quantifiable relationship between the required step length and the overflow depth and discharge, thereby offering a valuable tool for design purposes.

Relationship between changes in ground surface elevation and surface soil movement in areas around horizontal step works made from thin logs in a Japanese cypress forest

Relationship between changes in ground surface elevation and surface soil movement in areas around horizontal step works made from thin logs in a Japanese cypress forest

Weighted power summation and contrast normalization mechanisms account for short-latency eye movements to motion and disparity of sine-wave gratings and broadband visual stimuli in humans.

In this paper, we show that the model we proposed earlier to account for the disparity vergence eye movements (disparity vergence responses, or DVRs) in response to horizontal and vertical disparity steps of white noise visual stimuli also provides an excellent description of the short-latency ocular following responses (OFRs) to broadband stimuli in the visual motion domain. In addition, we reanalyzed the data and applied the model to several earlier studies that used sine-wave gratings (single or a combination of two or three gratings) and white noise stimuli. The model provides a very good account of all of these data. The model postulates that the short-latency eye movements-OFRs and DVRs-can be accounted for by the operation of two factors: an excitatory drive, determined by a weighted sum of contributions of stimulus Fourier components, scaled by a global contrast normalization mechanism. The output of the operation of these two factors is then nonlinearly scaled by the total contrast of the stimulus. Despite different roles of disparity (horizontal and vertical) and motion signals in visual scene analyses, the earliest processing stages of these different signals appear to be very similar.

Analysis of Wind Field Response Characteristics of Tethered Balloon Systems

Tethered balloon systems encounter various complex wind field environments during flight. To investigate the conditions under which the system can operate safely and smoothly, a longitudinal dynamic model for tethered balloon systems is established. The model incorporates a streamlined balloon shape with its aerodynamic center at the body’s center. Steady-state aerodynamic force coefficients are calculated through simulations and fitted to a function based on the angle of attack within a specified range. The complex cable model is simplified using the lumped mass method, considering the influence of branch cables on the main node position. Experimental results from windless oscillation tests on scaled tethered balloon systems are compared with numerical solutions obtained using the dynamic model under the same conditions, validating the feasibility of the model for simulating different wind field scenarios. Finally, the motion characteristics of tethered balloon systems in different wind fields are analyzed. The numerical simulation results show that in a horizontal step wind field, the cable tension and cable inclination angle increase with the wind speed, and the slower the wind field changes, the shorter the time required for system stabilization. Updrafts greatly increase the likelihood of balloon escape, while downdrafts greatly increase the likelihood of the system making contact with the ground. The findings of this study can provide a basis for selecting suitable wind field conditions and issuing risk warnings for tethered balloon systems.

Assessment of climate biases in OpenIFS version 43r3 across model horizontal resolutions and time steps

Abstract. We examine the impact of horizontal resolution and model time step on the climate of the OpenIFS version 43r3 atmospheric general circulation model. A series of simulations for the period 1979–2019 are conducted with various horizontal resolutions (i.e. ∼100, ∼50, and ∼25 km) while maintaining the same time step (i.e. 15 min) and using different time steps (i.e. 60, 30, and 15 min) at 100 km horizontal resolution. We find that the surface zonal wind bias is significantly reduced over certain regions such as the Southern Ocean and the Northern Hemisphere mid-latitudes and in tropical and subtropical regions at a high horizontal resolution (i.e. ∼25 km). Similar improvement is evident too when using a coarse-resolution model (∼100 km) with a smaller time step (i.e. 30 and 15 min). We also find improvements in Rossby wave amplitude and phase speed, as well as in weather regime patterns, when a smaller time step or higher horizontal resolution is used. The improvement in the wind bias when using the shorter time step is mostly due to an increase in shallow and mid-level convection that enhances vertical mixing in the lower troposphere. The enhanced mixing allows frictional effects to influence a deeper layer and reduces wind and wind speed throughout the troposphere. However, precipitation biases generally increase with higher horizontal resolutions or smaller time steps, whereas the surface air temperature bias exhibits a small improvement over North America and the eastern Eurasian continent. We argue that the bias improvement in the highest-horizontal-resolution (i.e. ∼25 km) configuration benefits from a combination of both the enhanced horizontal resolution and the shorter time step. In summary, we demonstrate that, by reducing the time step in the coarse-resolution (∼100 km) OpenIFS model, one can alleviate some climate biases at a lower cost than by increasing the horizontal resolution.

Effect of the Stepped Spillway Geometry on the Flow Energy Dissipation

In this research, flume experiments were conducted on stepped weirs to investigate the effect of step shape on the energy dissipation of flow. Four configurations with a constant number of steps were considered, namely, horizontal steps, inclined steps, horizontal steps with rounded sills, and ‎inclined steps with rounded sills. The slopes of inclined steps were 13% and 23%, and the diameters of the rounded sills of the step ends were 10 and 15 cm. The majority of previous studies focused on energy dissipation in stepped weirs in horizontal and inclined steps. In this research, new step geometries were used, such as horizontal steps with rounded sills and inclined steps with rounded sills. Dimensional analysis was applied to correlate the different variables affecting the flow hydraulics. Flow rates in the range of 0.61-9.12 lit/sec were used with each step shape. Results showed that the inclined steps with rounded sills had the highest flow energy dissipation in comparison to the other types. Rounded sills at the end of steps had more effective energy dissipation than did the horizontal step. However, the 23% inclination slope with rounded sills of a 7.5 cm radius was the most effective in dissipating flow energy. Doi: 10.28991/CEJ-2024-010-01-09 Full Text: PDF

Prefixes of bargraph paths

We extend the notion of bargraphs as first quadrant, semi-perimeter defined lattice paths to that of a bargraph prefix where we relax the bargraph defining parameters and allow the bargraph to extend into negative territory. A bargraph prefix is any initial section of a bargraph. Generating functions for the prefixes which separately track the number of up, down and horizontal steps are found. The asymptotics for the average height of the last prefix step in the different bargraph extensions is given.

Culex tarsalis Is a Competent Host of the Insect-Specific Alphavirus Eilat Virus (EILV).

Eilat virus (EILV) is an insect-specific alphavirus that has the potential to be developed into a tool to combat mosquito-borne pathogens. However, its mosquito host range and transmission routes are not well understood. Here, we fill this gap by investigating EILV's host competence and tissue tropism in five mosquito species: Aedes aegypti, Culex tarsalis, Anopheles gambiae, Anopheles stephensi, and Anopheles albimanus. Of the tested species, C. tarsalis was the most competent host for EILV. The virus was found in C. tarsalis ovaries, but no vertical or venereal transmission was observed. Culex tarsalis also transmitted EILV via saliva, suggesting the potential for horizontal transmission between an unknown vertebrate or invertebrate host. We found that reptile (turtle and snake) cell lines were not competent for EILV infection. We tested a potential invertebrate host (Manduca sexta caterpillars) but found they were not susceptible to EILV infection. Together, our results suggest that EILV could be developed as a tool to target pathogenic viruses that use Culex tarsalis as a vector. Our work sheds light on the infection and transmission dynamics of a poorly understood insect-specific virus and reveals it may infect a broader range of mosquito species than previously recognized. IMPORTANCE The recent discovery of insect-specific alphaviruses presents opportunities both to study the biology of virus host range and to develop them into tools against pathogenic arboviruses. Here, we characterize the host range and transmission of Eilat virus in five mosquito species. We find that Culex tarsalis-a vector of harmful human pathogens, including West Nile virus-is a competent host of Eilat virus. However, how this virus is transmitted between mosquitoes remains unclear. We find that Eilat virus infects the tissues necessary for both vertical and horizontal transmission-a crucial step in discerning how Eilat virus maintains itself in nature.

Enumerating symmetric pyramids in Motzkin paths

A path in the first quadrant of the xy-plane that starts at the origin having North-East steps (X), Horizontal steps (Z), South-East steps (Y), and that ends on the x-axis is called Motzkin. A maximal pyramid is a subpath of the form XhZmYh that cannot be extended to Xh + 1ZmYh + 1. It is symmetric if it cannot be extended to any of these subpaths: Xh + 1ZmYh or XhZmYh + 1. We use generating functions to enumerate symmetric pyramids and give the asymptotic behavior of the number of symmetric pyramids. Additionally, we give combinatorial arguments to count some of the mentioned aspects.

Experimental survey of static pressure in stepped chutes with inclined and horizontal steps equipped with end sills in nappe and skimming flow regimes

A spillway is one of the most important parts of a dam for controlling floods. Among different types of spillways, stepped spillways are one of the best energy dissipaters. Due to technological advances and the satisfaction of two elements for safe and low-cost construction, the use of stepped spillways has increased widely. Due to this, more studies are focused on stepped spillways. Researchers have made some efforts and proposed different methods to improve structural efficiency to dissipate energy. Modifications on step geometry, regarding flow regime type, are one of these efforts. Flow pressure and its fluctuations on the steps of the stepped spillways is one of the main factors affecting structural design and safety. In this experimental research, reverse inclined steps combined with the end sills have been applied in four degrees [0o (horizontal), 5o, 8o, and 11o] to obtain static pressure in both the nappe flow and skimming flow regimes of stepped spillways. Static pressure obtained from reverse inclined steps with end sills have been compared to the amount in the horizontal step. Results indicate a slight increase in the energy loss rate when reverse inclined steps have been applied in the nappe flow regime of stepped spillways.

Erratum to “Lefschetz Theory for Exterior Algebras and Fermionic Diagonal Coinvariants”

This erratum corrects the proof of the main result [1, Thm. 5.2] of [1, Sec. 5]. While this result is correct as stated, its proof is flawed. We adopt the notation of [1, Sec. 5]. The total order |$\prec $| is not a term order, so that [1, Lem. 5.3] loses meaning. In particular, [1, Lem. 5.1] is false because the depth |$d(\sigma )$| is not multiplicative. For |$n = 6$|⁠, the elements |$u, v \in \wedge \{ \Theta _{6}, \Xi _{6}\}$| given by |$u=\xi _{1} \theta _{3}\xi _{3} \theta _{4} \theta _{5} \xi _{5}$| and |$v=\theta _{1} \theta _{2}\xi _{2} \theta _{4} \theta _{6} \xi _{6}$| have the following lattice path representations as in [1, Sec. 5]: We correct the proof of [1, Thm. 5.2] as follows. We shall calculate a Gröbner basis for the ideal |$I_{n} = \langle \delta _{n}\rangle \subset \wedge \{\Theta _{n}, \Xi _{n} \}$| where |$\delta _{n}= \sum _{i=1}^{n} \theta _{i} \xi _{i}$| with respect to the lexicographical term order |$<_{\textrm{lex}}$|⁠. For each Motzkin path |$\sigma $| as in [1, Sec. 5], we define |$j(\sigma )$| to be the |$x$|-coordinate where the depth |$d(\sigma )$| is achieved the 1st time. We have |$d(\sigma )=0$| if and only if |$j(\sigma )=0$|⁠. If |$u, v$| are the Motzkin paths (or monomials) in Example 1, then |$j(u)=5$| and |$j(v)=2$|⁠. Given a Motzkin path |$\sigma =(s_{1}, s_{2},\dots , s_{n})$| and |$i \leq n$|⁠, we define |$k_{i}$| to be the difference between the |$y$|-coordinate of the starting point of |$s_{i}$| and |$d(\sigma )$|⁠. For example, |$k_{1}=-d(\sigma )$| and |$k_{j(\sigma )+1}=0$|⁠. For |$i\leq j(\sigma )$|⁠, we introduce the exterior algebra elements ... ... The initial ideal |$\operatorname{in}_{lex}(\delta _{n}^{k})$| with respect the lexicographical term order contains all monomials |$\sigma $| with depth |$d(\sigma )\leq -k$|⁠. We claim that the leading monomial of |$p(\sigma )\delta _{n}^{-d(\sigma )}$| divides the monomial |$\textrm{wt}(\sigma )$|⁠, and we prove this statement for all |$n$| by induction on |$j(\sigma )$|⁠. The base case |$j(\sigma )=0$| is trivial because all monomials belong to the ideal generated by |$\delta _{n}^{0}=1$|⁠. For the inductive step, we remove the 1st step |$s_{1}$| from |$\sigma $| to get a new path |$\tau =(s_{2}, \dots , s_{n})$| involving only the variables |$\theta _{2}, \dots , \theta _{n}, \xi _{2}, \dots , \xi _{n}$|⁠. Notice that |$p(\sigma )=p_{1}(\sigma )p(\tau )$|⁠. We divide proof in three cases according to the 1st step |$s_{1}$|⁠. Case 1:|$s_{1} = (1,1)$|is an up step. We have |$d(\tau )=d(\sigma )-1$|⁠, |$\textrm{wt}(\sigma )=\textrm{wt}(\tau )$|⁠, and ... Case 2:|$s_{1} = (1,0)$|is a horizontal step. We assume that the horizontal step |$s_{1}$| is labelled with |$\theta $|⁠; the other case is identical. We have |$d(\tau )=d(\sigma )$|⁠, |$\textrm{wt}(\sigma )=\theta _{1} \textrm{wt}(\tau )$|⁠, and ... ... Case 3:|$s_{1} = (1,-1)$|is a down step. We have |$d(\tau )=d(\sigma )+1$|⁠, |$\textrm{wt}(\sigma )=\theta _{1}\xi _{1} \textrm{wt}(\tau )$|⁠, |$p(\sigma )=p(\tau )$|⁠, and ... We conclude that |$\textrm{wt}(\sigma ) \in \textrm{in}_{\textrm{lex}}(\delta _{n}^{-d(\sigma )}) \subseteq \textrm{in}_{\textrm{lex}}(\delta _{n}^{k})$| for all |$k \leq -d(\sigma )$| and the proof is complete. The above theorem substitutes [1, Lem. 5.3]. The 2nd part of the proof of [1, Thm. 5.2] is correct and can be left unchanged. The set |$\{p(\sigma )\delta _{n} \mid \sigma \textnormal{ s.t.} d(\sigma )=-1\}$| is a Gröbner basis for the ideal |$I_{n}= \langle \delta _{n} \rangle $| with respect to the lexicographical term order.

Emerging concepts in heart failure management and treatment: focus on current guideline-directed medical therapy for heart failure with reduced ejection fraction.

One of the most relevant and differentiating aspects provided by the 2021 European Society of Cardiology guidelines for the diagnosis and treatment of acute and chronic heart failure is the retraction of the historical stepped and vertical pharmacological treatment scheme for heart failure with reduced ejection fraction (HFrEF). Subsequently, it was replaced by an updated algorithm that places four therapeutic families in the same initial horizontal step with an equally high degree of recommendation (class I). In this context, these four pillars, which have demonstrated a significant reduction in mortality and hospitalizations in patients with HFrEF, include (1) angiotensin-converting enzyme inhibitors (ACEi)/angiotensin receptor blockers (ARB)/angiotensin II receptor-neprilysin inhibitors (ARNi), (2) beta blockers, (3) mineralocorticoid receptor antagonists (MRA) and (4) sodium-glucose cotransporter 2 inhibitors (SGLT2is) as the main novelty. This manuscript reviews the current therapeutic algorithm with a special focus on the therapeutic value of adding an MRA (still underused in both clinical trials and real world), changing an ACEi/ARB for an ARNi and incorporating an SGLT2i in patients with HFrEF. This article is part of the Emerging concepts in heart failure management and treatment Special Issue: https://www.drugsincontext.com/special_issues/emerging-concepts-in-heart-failure-management-and-treatment.

Тестирование и перспективы технологии прогнозирования загрязнения воздуха с применением химических транспортных моделей CHIMERE и COSMO-Ru2ART

The technology for numerical air pollution prediction operating in the Hydrometeorological Center of Russia is based on the calculations with CHIMERE and COSMO-ART chemical transport models (CTMs) on a grid with a horizontal step of 2.2 km using the EMEP inventory data on atmospheric emissions updated in 2013 and meteorological data of the COSMO-Ru2 atmosphere model. The paper presents the results of testing model forecasts of pollutant (NO2, CO, PM10, O3) concentrations based on continuous pollution observations in the Moscow region for 12 months. A predominant overestimation of concentrations by the CHIMERE and an underestimation by the COSMO-ART were revealed. Both CTMs mainly underestimate pollution in transport-type areas. The seasonal variability of model deviations with a sign change for each model and each pollutant was identified. The largest model deviations were observed under abnormal weather conditions: during summer heat waves and spring advection of dusty air. Taking into account the model errors established for each CTM, recommendations are formulated for producing an operational consolidated forecast using the integration of simulations with the two CTMs. The development of the technology for numerical air pollution prediction using modified CTM versions and EMEP emissions updated in 2019 on a 0.1×0.1° grid is discussed. Keywords: air pollution, numerical forecast, chemical transport model, CHIMERE, COSMO-Ru2ART, emissions, EMEP, testing

Investigation of Energy Dissipation Rate of Stepped Vertical Overfall (SVO) Spillway Using Physical Modeling and Soft Computing Techniques

In the present study a physical model of a stepped vertical overfall (SVO) spillway is proposed and designed as a novel combination of a free overfall spillway with horizontal steps. First, the hydraulic design characteristics of the proposed spillway were discussed using a laboratory-scaled model. Effective parameters on the energy dissipation rate were defined as the relative critical depth, Froude number, number of steps, and dimensionless steps' geometry parameter using dimensional analysis. The energy dissipation rate of the stepped vertical overfall spillway is measured using a waterwheel laboratory setup. Different geometry and hydraulic scenarios were used to assess the energy dissipation rate variation of the proposed spillway. Furthermore, Support Vector Regression and Random Forest Regression methods were used to estimate the energy dissipation of the proposed structure. Investigating the energy dissipation rate of 27 geometry scenarios with the available range of discharge revealed that the energy dissipation rate against the water's relative depth inside the SVO spillway follows a gradually increasing trend ranging between 88.53% to 98.06%. Also, random forest regression algorithm showed more accurate prediction performance than support vector regression approach with RMSE = 0.128 and R2 = 0.99 in training stage and RMSE = 0.115 and R2 = 0.99 in testing stage. The support vector regression model estimated the proposed spillway's energy dissipation rate with an accuracy of RMSE = 0.67 and R2 = 0.88 in training stage and RMSE = 0.61 and R2 = 0.9 in testing stage.

Research on Mechanical Properties and Damage Constitutive Model of Water-Bearing Coal

Many water-related problems are confronted in coal mining, and the mechanical properties of coal inevitably deteriorate due to water–rock interactions. Therefore, it is necessary to study the macroscopic mechanical properties and damage constitutive model of water-bearing coal for safe mining. The uniaxial compression tests of raw coal samples with five moisture contents under four loading rates were carried out. Based on the test, the Drucker–Prager criterion is introduced to describe the failure law of micro-elements; assuming that the strength of micro-elements obeys a two-parameter Weibull distribution, a three-stage damage constitutive model is established. The model, existing model, and test curves were compared, and four indicators were introduced to evaluate the fitting effect. The results demonstrate that the stress–strain curve has a near horizontal step before the elastic stage, and its length is positively correlated with the moisture content ω. With the increase in ω, the peak strain increases linearly, and the compressive strength and Young’s modulus first increase and then decrease. The loading rate does not change the type of the fitting function between the mechanical parameters and ω. The three-stage model is more universal and can better fit the full stress–strain curve of water-bearing coal under uniaxial compression.

A Novel Suppression Method of Height Drift for Pedestrian Navigation With a Circular Hypotheses on Terrain Slope

The inertial navigation system (INS) based on zero velocity update (ZUPT) is a traditional method for pedestrian positioning. The height information of INS will drift over time. A common solution is to use external height information, such as barometer output, to compensate the drift. However, this method is easily affected by air temperature, wind speed, etc. A new geometric model method is proposed in this study to suppress the height drift. The inertial sensor is mounted at the shoe. The natural terrain with continuous slope changing is assumed to be circular arc-shaped every single step. A geometric model of three-dimensional step length is established using the horizontal step length and the pitch angle of the shoe. Four experiments were designed on flat, sloped, and natural terrains, respectively. The experimental results show that the accuracy of the proposed method is improved by more than 90% and 70% compared to the classical INS method and the INS method incorporating a barometer, respectively. The proposed method needs no external signal and is not influenced by the external environment. Furthermore, lightweight calculations make it appropriate for real-time applications.

Kinetic and Kinematic Effects of Asymmetrical Loading of the Lower Limb During High-Speed Running.

Light lower-limb wearable resistance has little effect on running biomechanics. However, asymmetrical wearable resistance may potentially alter the kinetics and kinematics of high speed, enabling greater loading or unloading of an injured or rehabilitative lower limb. A cross-sectional study design was used to quantify the influence of asymmetric calf loading on the kinematics and kinetics during 90% maximum sprinting velocity. Following a familiarization session, 12 (male = 7 and female = 5) physically active volunteers ran at 90% of maximal velocity. In random order, participants ran with zero (0) wearable resistance and with loads of 300g (L300) and 600g (L600) fixed to one shank. A nonmotorized treadmill quantified vertical and horizontal kinetics and step kinematics. The kinetics and kinematics of the loaded (L0, L300, and L600) and unloaded (UL; UL0, UL300, and UL600) limbs were compared. Vertical step ground reaction force of the loaded limb tended to increase between unloaded and 300 and 600 conditions (effect size [ES] = 0.48 to 0.76, all P ≤ .12), while the horizontal step force of the UL tended to decrease (ES = 0.54 to 1.32, all P ≤ .09) with greater external loading. Step length increased in the UL in 0 versus 300 and 600 conditions (ES = 0.60 to 0.70, all P ≤ .06). Step frequency decreased in the ULs in unloaded versus 300 and 600 conditions (ES = 0.73 to 1.10, all P ≤ .03). Mean step velocity tended to be greater in the ULs than the 300 and 600 conditions (ES = 0.52 to 1.01, all P ≤ .10). Only 4 of 16 variables were significantly different between the 300 and 600 conditions. Asymmetrical shank resistance could be used during high-speed running to reduce or increase the kinetic loading of an injured/rehabilitative limb during return to play protocols. Asymmetrical wearable resistance could also be used to alter step kinematics in runners with known asymmetries. Finally, meaningful alterations in high-speed running biomechanics can be achieved with only 300g of shank loading.

Time structure of pencil beam scanning proton FLASH beams measured with scintillator detectors and compared with log files.

Key factors in FLASH treatments are the ultra-high dose rate (UHDR) and the time structure of the beam delivery. Measurement of the time structure in pencil beam scanning (PBS) proton FLASH treatments is challenging for many types of detectors since high temporal resolution is needed. In this study, a fast scintillator detector system was developed and used to measure the individual spot durations as well as the time when the beam moves between two positions (transition duration) during PBS proton FLASH and UHDR treatments. The spot durations were compared with machine log-file recordings. A detector system based on inorganic scintillating crystals was developed. The system consisted of four detector probes made of a sub-millimeter ZnSe:O crystal that was coupled via an optical fiber to an optical reader with 50kHz sampling rate. The detector system was used in two experiments, both performed with a PBS proton beam with 250MeV beam energy and 215nA requested nozzle beam current. The sampling rate enabled multiple measurements during each spot delivery and during the beam transition between spots. First, the detector was tested in a phantom experiment, where a total of 305 scan sequences were delivered to the four detectors. The number of spots delivered without beam interruption in a single scan sequence ranged from one to 35. The spot duration and transition duration were measured for each individual spot. Secondly, the detector system was used in vivo in preclinical experiments with FLASH irradiation of mouse legs placed in the entrance plateau of the beam. A single detector was placed 1cm downstream of the irradiated mouse leg. The mouse dose ranged from 30.5 to 44.2Gy and the field consisted of 35 spots. The spot durations as well as the mean dose rate (field dose divided by the measured field duration) for each mouse were determined using the detector and then compared with the corresponding log files. The phantom experiment showed that the logged total duration of an uninterrupted spot sequence was consistently shorter than the measured duration with a difference of -0.252ms (95% confidence interval: [-0.255, -0.249ms]). This corresponded to 0.05%-0.07% of the spot sequence duration in the mice experiments. For individual spots, the mean±1SD difference between logged and measured spot duration was -0.39±0.05ms for the first spot in a sequence, 0.13±0.04ms for the last spot in a sequence, and -0.0017±0.09ms for the intermediate spots in a sequence. The measured spot transition durations were 0.20±0.04ms (5.1mm horizontal steps) and 0.50±0.04ms (5.0mm vertical steps). For the mouse experiments, the mean dose rate calculated from the measured field duration was 84.1-92.5Gy/s. It agreed with log files with a root mean square difference of 0.02Gy/s. Fiber-coupled scintillator detectors were designed with sufficient temporal resolution to measure the spot and transition duration during PBS proton UHDR deliveries. Their small volume makes them feasible for in vivo use in preclinical FLASH studies. The logged spot durations were in excellent agreement with measurements but showed small systematic errors in the logged duration for the first and last spot in a sequence.

Bottom-Pressure Development Due to an Abrupt Slope Reduction at Stepped Spillways

Fluctuating bottom-pressures on stepped chutes are relevant for the spillway design. An abrupt slope reduction causes a local alteration of the bottom-pressure development. Little information is available regarding the air–water flow properties near an abrupt slope reduction on stepped chutes, particularly on the local pressure evolution. Nevertheless, the option of providing a chute slope reduction may be of interest in spillway layout. The experiments presented herein include pressure distributions on both vertical and horizontal step faces, subsequent to an abrupt slope reduction on stepped chutes. A relatively large-scale physical model including abrupt slope reductions from 50° to 18.6° and from 50° to 30° was used, operated with skimming flow. The data indicate a substantial influence of the tested slope reductions on the bottom-pressure development. In the vicinity of the slope reduction, the mean pressure head near the edge of the horizontal step face reached 0.4 to 0.6 times the velocity head upstream of the slope reduction, for critical flow depths normalized by the step height ranging between 2.6 and 4.6.

Planar Five-link Biped Robot Movement over a Stepped Surface

Modeling the anthropomorphic robot movement is of great interest to researchers all over the world. At the same time, the movement control of a walking mechanism is always a high dimension challenge. The difficulty with the anthropomorphic robot control is also caused by the fact that such a mechanism has always a hybrid dynamics and represents a sequential change of two phases – the single support phase and the double support phase (phase of changing robot’s leg). At the single support phase and at another phase the behavior of the biped robot is described by a system of ordinary differential equations and by a system of linear algebraic equations, respectively.The task of biped robot movement control has been studied in detail for the case when the robot moves over the horizontal surface. Obstacles make the task significantly complicated. The paper considers the movement control of the biped robot over the surface that is a periodic alternation of horizontal sections and obstacles. The obstacles represent steps of the same height known. It is assumed that the lengths of horizontal sections and steps are known as well. The objective is to create a control that provides robot’s periodic movement over the specified surface according to inherent characteristics of a walking human.For the single support phase, the outputs are proposed, the equality of which to zero corresponds to the robot’s movement with a given set of characteristics. The paper presents the feedback controls that stabilize the proposed outputs for a finite amount of time. By choosing the feedback parameters, it is possible to adjust the stabilization time so that the outputs become equal to zero when reached the end of each step.It is shown that for the chosen control law, the problem of constructing the control of robot’s periodic movement is reduced to the solution of a nonlinear equation. In the paper, we discuss the approaches to solving this equation and present the results of numerical simulation.The results obtained can be used to solve the problem of providing control of the biped robot movement over the surfaces with obstacles of a more complicated shape.Modeling the anthropomorphic robot movement is of great interest to researchers all over the world. At the same time, the movement control of a walking mechanism is always a high dimension challenge. The difficulty with the anthropomorphic robot control is also caused by the fact that such a mechanism has always a hybrid dynamics and represents a sequential change of two phases – the single support phase and the double support phase (phase of changing robot’s leg). At the single support phase and at another phase the behavior of the biped robot is described by a system of ordinary differential equations and by a system of linear algebraic equations, respectively.The task of biped robot movement control has been studied in detail for the case when the robot moves over the horizontal surface. Obstacles make the task significantly complicated. The paper considers the movement control of the biped robot over the surface that is a periodic alternation of horizontal sections and obstacles. The obstacles represent steps of the same height known. It is assumed that the lengths of horizontal sections and steps are known as well. The objective is to create a control that provides robot’s periodic movement over the specified surface according to inherent characteristics of a walking human.For the single support phase, the outputs are proposed, the equality of which to zero corresponds to the robot’s movement with a given set of characteristics. The paper presents the feedback controls that stabilize the proposed outputs for a finite amount of time. By choosing the feedback parameters, it is possible to adjust the stabilization time so that the outputs become equal to zero when reached the end of each step.It is shown that for the chosen control law, the problem of constructing the control of robot’s periodic movement is reduced to the solution of a nonlinear equation. In the paper, we discuss the approaches to solving this equation and present the results of numerical simulation.The results obtained can be used to solve the problem of providing control of the biped robot movement over the surfaces with obstacles of a more complicated shape.