Travel Length Research Articles

Autonomous Rear Parking via Rapidly Exploring Random-Tree-Based Reinforcement Learning.

This study addresses the problem of autonomous rear parking (ARP) for car-like nonholonomic vehicles. ARP includes path planning to generate an efficient collision-free path from the start point to the target parking slot and path following to produce control inputs to stably follow the generated path. This paper proposes an efficient ARP method that consists of the following five components: (1) OpenAI Gym environment for training the reinforcement learning agent, (2) path planning based on rapidly exploring random trees, (3) path following based on model predictive control, (4) reinforcement learning based on the Markov decision process, and (5) travel length estimation between the start and the goal points. The evaluation results in OpenAI Gym show that the proposed ARP method can successfully be used by minimizing the difference between the reference points and trajectories produced by the proposed method.

Parametric design analysis of a multi-level 3D manifolded microchannel cooler via reduced order numerical modeling

Waste heat flux from power dense electronics is expected to reach > 1 kW/cm2 in the next few decades, and they will require novel cooler designs with low thermal resistance, that can simultaneously dissipate large levels of heat and have high coefficient of performance (COP). 2D straight microchannel cold plates (CP) are an industrial go-to solution for active heat dissipation needs, but they suffer from a major drawback – very high pump pressure is required to force large quantities of fluid through miniscule channels in the CP and thus these coolers are very inefficient, achieving low COP. Recently, manifolded micro-coolers (MMC) have become popular which use a second manifold layer to distribute the fluid in 3D within the CP, thus shortening fluid travel length within the miniscule CP channels and significantly reducing the total device pressure drop. In this study, we first introduce a novel two-level manifold design which boasts a potential of > 2x improvement in COP compared to conventional single-level manifold concept without affecting the thermal performance. Recognizing the difficulty in simulating large area full MMCs, we then aim to simplify the 2-level MMC geometry into reduced order models to bring down simulation cost at an expense of accuracy. Two models were considered, the widely popular and convenient to use Single Cold Plate U-bend Channel (SCPUC) model which only simulates the CP channels, and the slightly more complicated Single Manifold Channel (SMC) model which also considers the effect of the manifold. The SMC model simulations were first validated against full device simulations for different heater footprint sizes (25, 100, 400 mm2) to establish accuracy and it was found that the SMC model could predict thermal performances of all device sizes with a nominal inaccuracy of 5%. In contrast, the widely accepted SCPUC model produced highly inaccurate (as high as 25–45%) predictions for thermal performance of the MMCs. The two models were then used under an extreme heat flux load of 800 W/cm2 and 0.2 liter per min (lpm) device flow rate, to simulate 54 different 2-level MMCs obtained by varying important geometric parameters on the manifold and cold plate side. Detailed analysis was performed to explain the trends in thermal performance and pressure drop with different geometric parameters. Finally, two pareto curves were reported, one between thermal resistance and pressure drop, and the other between COP and device size. It was seen that the proposed 2-level MMC showed record high COP as compared to state-of-the-art single-level MMCs. We hope that this study will act as a design guide for MMCs as well as act as a performance repository for a wide range and combinations of geometries of 2-level manifold structures.

Coupling of Photonic Crystal Surface Modes

Guiding and evanescent coupling properties of surface modes bound to the interfaces of two-dimensional photonic crystals in close proximity are numerically demonstrated. Interacting photonic crystals are composed of silicon pillars in air, where their outermost layers facing each other are annular. Surface modes are identified through supercell band structure computations, while their excitation by the electromagnetic waves through a perpendicular insertion waveguide is demonstrated using finite-difference time-domain simulations. Lifting the degeneracy between the surface modes as a consequence of bringing two identical photonic crystal surfaces to a sufficient distance results in evanescent coupling in a beating manner whose beat length linearly varies between 10 and 20 periods up to a frequency at which both surface modes travel with the same group velocity. The surface mode coupling phenomenon could be employed either to enhance sensitivity or to reduce device size in bio/chemical sensor applications since the effective travelling length of surface waves increases by about 3.5 times due to evanescent coupling.

Focus on software, data acquisition, and instrumentation

Focus on software, data acquisition, and instrumentation

Seasonal variations in Home Range Size of Capped Langur (Trachypithecus pileatus) in a degraded habitat in Assam, India

A group of capped langurs, Trachypithecus pileatus comprising eight individuals was studied in Sri Surya Pahar, a degraded habitat in Goalpara district of Assam to record the seasonal variations in distance travelled, home range, and habitat utilization through direct observation supplemented by Geographical Information system (GIS). Scan sampling method was followed to record data on ranging behaviour. Seasonality in the home range size was evident and significant (P<0.01), it was 20 ha in winter, 17 ha in pre-monsoon, 17.75 ha in monsoon and 16.25 ha in retreating monsoon. The mean daily travel distance varied significantly (P<0.01), it was 375 m in retreating monsoon to 490 m in winter. The mean daily travel length was 439 m and the total annual home range size was 38.25 ha. The variation of home range size was correlated with the distribution and abundance of food resources. Home range size and daily travel distance showed significant seasonal variations. In both the cases the ranging patterns were longer during the winter season. This may be due to shortage of new leaves during winter, which is the preferred food item of capped langur. Spatial availability of the different food resources over different seasons may also be a reason for significant changes in ranging pattern during different seasons. The present data on home range size and ranging pattern of capped langur in degraded habitat could be useful for improvement of habitat and the conservation of this endangered species in Assam.

Resilience and recovery of public transport use during COVID-19

To better understand how public transport use varied during the first year of COVID-19, we define and measure travel behavior resilience. With trip records between November 2019 and September 2020 in Kunming, China, we identify people who relied on traveling by subway both before and after the first pandemic wave. We investigate whether and how travelers recover to their pre-pandemic mobility level. We find that public transport use recovered slowly, as urban mobility is a result of urban functionality, transport supply, social context, and inter-personal differences. In general, urban mobility represents a strengthened revisiting tendency during COVID-19, as individual’s trips occur within a more limited space. We confirm that travel behavior resilience differs by groups. Commuters recover travel frequency and length, while older people decrease frequency but retain activity space. The study suggests that policymakers take group heterogeneity and travel behavior resilience into account for transport management and city restoration.

Improved engineered scoring system for bicycle lane mapping development

This paper intends to present the development of the Improved Bicycle Lane Engineered Scoring System (iBLESS). The iBLESS consists of a numerical ranking table that compares traffic volume data; speed limit; number of lanes; road width; presence of the vehicle parking; presence of night street light; road grade; overall travel length; and presence of existing bicycle lanes that is utilized to design and map the optimum achievable locations for the implementation of bicycle lanes. The City of Tyler, Texas, is utilizing the iBLESS to design a Hub-and-Spoke bicycle lane network around the city. The current map design utilizing the iBLESS is comprised of eleven bicycle spokes, and seven bicycle spoke-connections, reaching a total distance of over 55 miles (88.5km) of bicycle lanes. The presence of bicycle lanes will extend throughout the entire city, resulting in the introduction of a new mode of transportation to the City of Tyler. Results indicate that the iBLESS is a simple and useful methodology to compare and analyze roads for bicycle lane development. Since this system selects the optimal road candidates, the bicycle users feel more comfortable using bicycle lanes as opposed to riding in a roadway.

KEPUASAN PENGGUNA HALTE TRANSIT TRANSJAKARTA DENGAN PENDEKATAN HETEROGENEOUS CUSTOMER SATISFACTION INDEX (HCSI)

One factor that marks the quality of public transport is the integration of services between or inter modes, especially through interchange shelters. Koridor 1 Trans Jakarta (TJ) is an important corridor because it has an interchange shelter, which serves and relates most with other TJ routes. However, no studies have examined the user satisfaction level in interchange shelters. This Survey was conducted from Koridor 1 TJ interchange shelter passengers (N=252): Bendungan Hilir, Dukuh Atas, Harmoni, Monas, and Kota, by Heterogeneous Customer Satisfaction Index (HCSI). The results showed the level of customer satisfaction of Koridor 1 Trans Jakarta (TJ) can be categorized as good. There are four attributes of the services that have the highest satisfaction level: Ticket prices, Special female passenger area, Ease of buying tickets, and Interchange information. Otherwise, other attributes have the lowest satisfaction levels: Mix traffic, Length of travel, Waiting time at the bus stop, Standing position comfort on the bus, Noise on the bus, as well Queue line, and disembark direction on shelter.

Travel-Associated Venous Thromboembolism.

Long-distance travel is assumed to be a risk factor for venous thromboembolism (VTE). However, the available data have not clearly demonstrated the strength of this relationship, nor have they shown evidence for the role of thromboprophylaxis. We performed a systematic review of the literature. We also summarized available guidelines from 5 groups. We found 18 studies that addressed this question. Based on the data presented in the review, we conclude that there is an association between VTE and length of travel, but this association is mild to moderate in effect size with odds ratios between 1.1 and 4. A dose-response relationship between VTE and travel time was identified, with a 26% higher risk for every 2 h of air travel (P=0.005) starting after 4 h. The quality of evidence for both travel length and thromboprophylaxis was low. However, low-risk prophylactic measures such as graduated compression stockings were shown to be effective in VTE prevention. There is heterogeneity among the different practice guidelines. The guidelines generally concur that no prophylaxis is necessary in travelers without known thrombosis risk factors and advocate for conservative treatment such as compression stockings over pharmacologic prophylaxis. We conclude air travel is a risk factor for VTE and that there is a dose relationship starting at 4 h. For patients with risk factors, graduated compression stockings are effective prophylaxis.

Valuasi Ekonomi Terhadap Penyedia Jasa Wisata Alam di Taman Hutan Raya Sultan Adam

This study aims to determine the factors that affect the number of visits and the economic value of the Tahura Sultan Adam tourism object. Data collection techniques are observation and interviews with a questionnaire. The data were processed using descriptive analysis, multiple linear regression, and the consumer surplus formulae. From the research, it is known that the characteristics and perceptions of visitors vary widely, consisting of age, regional origin, gender, marital status, education level, occupation, total income, type of vehicle, number of groups, information about tourist attractions, tourist attractions, motivation, additional facilities, security, officer services, accessibility, cleanliness, air pollution, admission tickets, and willingness to pay. The collected data were analyzed using multiple linear regression analysis models. From the research results, three factors significantly affect the number of visits to Tahura Sultan Adam, namely income, travel costs, and length of travel. From the calculation, results can be seen in surplus-value consumer travel cost method individual visitation Rp 179 153 and subsequently obtained the economic value of Rp 17,610,381,594 annually

An augmented Lagrangian relaxation method for the mean-standard deviation based vehicle routing problem

With the ever-increasing trip demand and limited transportation resource, traffic congestions remain a tricky problem. Under traffic congestions, travel times are unstable and variable in a real-world network. When we conduct many time-sensitive vehicle routing optimizations such as vaccine transportation, it is essential to consider the travel time variability in these optimizations. However, most previous vehicle routing studies neglected the travel time variability and adopted the expected travel times or lengths of links. The historical travel times of multiple days allow us to access and describe the travel time variability. We can easily obtain the travel time means and standard deviations of links from these data. This study applies these two statistical indicators to vehicle routing optimization and concentrates on a mean-standard deviation based vehicle routing model. This model has a nonlinear and concave objective function that dramatically increases the problem complexity. We develop a novel augmented Lagrangian relaxation approach for this problem. A lower bound is constructed for this problem by applying the Lagrangian relaxation and decomposition technique twice. To break the inherent symmetry of this problem, we use the augmented Lagrangian relaxation method with block coordinate descent, linearization, and Lagrangian substitution techniques to achieve high-quality feasible solutions. Thus, the relative gap between the lower and upper bounds can be evaluated and reduced in the solving procedure. We implement the proposed method on the datasets modified from the standard benchmark instances. The average relative gaps of instances in sets A and P are 8.8% and 7.6%, respectively.

Amorphous TiO2 beats P25 in visible light photo-catalytic performance due to both total-internal-reflection boosted solar photothermal conversion and negative temperature coefficient of the forbidden bandwidth

In this work, visible light total reflective SiO2 @TiO2 core-shell catalyst was synthesized by atomic layer deposition (ALD). This core-shell catalyst processing a total reflection character against full visible light favors the total effective traveling length of visible light inside the TiO2 shell. Subsequently, higher catalyst temperature under visible light irradiation expands the light absorbing window of amorphous TiO2 to full visible light due to its negative temperature coefficient of the forbidden bandwidth. Boosted photothermal conversion efficiency (145% that of amorphous TiO2) can be achieved to exhibit a 17β-estrogen degradation rate 1.5 times that of the commercial P25 (a mixed TiO2 crystal of 20% rutile and 80% anatase) and 2.9 times catalytic velocity that of P25. The boosted catalytic performance of SiO2 @TiO2 core-shell catalyst is attributed by expanded visible-light absorption, boosted photothermal conversion efficiency, and prolonged carrier lifetime.

A two-nozzle cable-driven parallel robot for 3D printing building construction: path optimization and vibration analysis

This paper proposes a novel two-nozzle cable-driven parallel robot (CDPR) for 3D printing building construction. This system has two independently moving nozzles mounted on the existing printing head. Thus, the printing time can be reduced dramatically with this system as the travel path of the printing head can be reduced to almost half thanks to those two nozzles that print almost half of the printing contour. To fully take advantage of two nozzle structures effectively, the path of the printing head is optimized to secure the minimum travel length of both the printing head and two nozzles. The smoothness of the optimal path is secured by applying the non-uniform rational B-splines (NURBS). In addition, free vibration of the proposed CDPR printer’s structure is analyzed to improve the printing quality and help the control of the proposed CDPR by using a finite element formulation of cables of the proposed robot. From the analysis results, the critical design guide—stiffness of the proposed structure could be raised by increasing the minimum cable tension in the tension distribution optimization algorithm—was obtained as well.

Propagation and rupture of elastoviscoplastic liquid plugs in airway reopening model

The propagation and rupture of mucus plugs in human lungs is investigated experimentally by injecting synthetic mucus in a pre-wetted capillary tube. The rheology of our test liquid is thoroughly characterized, and four samples of synthetic mucus are considered in order to reproduce elastoviscoplastic regimes of physiological interest for airway reopening. Our experiments demonstrate the significant impact of the viscoplasticity and viscoelasticity of mucus. In support to our experiments, we propose a one-dimensional reduced-order model that takes into account capillarity, and elastoviscoplasticity. Our model manages to capture the cross-section averaged dynamics of the liquid plug and is used to elucidate and interpret the experimental evidence. Relying on it, we show that the liquid film thickening due to non-Newtonian effects favors plug rupture, whereas the increase of the effective viscosity due to higher yield stresses hinders plug rupture. As a result of such two effects, increasing the polymeric concentration in the mucus phase leads to a net increase of the rupture time and traveling length. Hence, non-Newtonian effects hinder airway reopening.

Empirical relationships of the landslides in the Chinese Loess Plateau and affect factors analysis

The CLP (Chinese Loess Plateau) is one of the most densely distributed landslides areas. The empirical relationships of the landslides in the CLP remain unclear, and its influencing factors are controversial. According to regional landslide data, this paper studies the relationships and discusses the factors affecting landslides in the CLP. The results show that the area (A) -volume (V) of landslides follows a power law trend described by V = 1.53 A 1.19 and the frequency distribution range of H/L (height drop (H)/travel length (L)) is between 0.2 and 1.0, more specifically between 0.2 and 0.4, accounting for 26.1% of the total landslides, indicating that the landslides primarily belong to long run-out landslides. The function of V and H/L of the landslides is followed by H/L = 2.39 V −0.102. About 87% of the landslide is distributed within the equilibrium or mature stages of the watershed. The landslide’s size increases, and the slope of the landslides are steeper with an increase in HI (hypsometric integral). Meanwhile, the loess thickness, human activities, and slope effects on landslides induce landslide occurrence and have positive and negative effects on the landslides within the CLP. With climate change, the risk of landslides will increase in the CLP.

THE STATE OF COMMUNICATIONS IN THE RUDKIV DISTRICT OF WUPR (NOVEMBER 1918 – MAY 1919)

The article analyzes the state of communications in the Rudkiv District of the West Ukrainian People's Republic during November 1918 – May 1919. It highlights the importance of the means of communication for the functioning of the state and society; pays attention to crisis phenomena; and investigates the reasons for their occurrence. It is demonstrated that, for a number of reasons, it was not possible to establish an effective railway connection in the county immediately. On the one hand, the article notices such problems of a state scale as personnel, fuel and material hunger, abuse of power by civil servants, and disorganization of the movement. On the other hand, it is indicated that the functioning of the local railway had its own peculiarities: as a result of the loss of Lviv, the duration and length of travel significantly increased; there was no record of theft of railway property in the district; but there were cases of sabotage among railway workers. The measures taken by the government to resolve the crisis are revealed. It is demonstrated that other means of transportation, primarily ordinary roads, despite the repair work of the military authorities and the civilians, were in an unsatisfactory condition due to natural disasters, negligence, or abuse of local residents. The example of the functioning of local post, telegraph and telephone networks shows the reflection of such national trends as the protection and restoration of telegraph lines, the slow creation of post offices and governments, and difficulties with the Ukrainization of state emblems on a regional scale. Keywords: Western Ukrainian People's Republic, Rudkiv District, means of communication, railway, postal service, telegraph and telephone networks.

Assessing profile damage of uncoated and AlTiN coated FSW tools after successive travel on AA6061-T6 plate

The quantitative assessment of profile damage of square (SQ) and threaded with three intermittent flat faces (TIF) tool pin was appraised and presented for both uncoated and AlTiN coated tools during friction stir passes on AA6061-T6 plates successively after different travel lengths. Significantly lower profile damage with small amount of profile twisting was noted for TIF tool pin as compared to the SQ tool pin owing to lower force and torque, as predicted by finite element (FE) results. For AlTiN coated tools, the pin profile damage reduced significantly due to high wear resistance, hardness and good adhesion of coating with the tool substrate. Significantly lower temperature rise was noted in the AlTiN coated tool compared to the uncoated tool. A mathematical approach to predict the heat generation was presented and predicted temperatures were found in good agreement with FE results. Plastic deformation of sharp corners, adhesion and abrasion wear of flat faces, and initiation of crack near tool pin-shoulder interface was noted in uncoated tools however, they got reduced in the AlTiN coated tool. The delamination of coating near the tool pin edge, flat surfaces and near the tool pin-shoulder interface was noted due to dislodging of adhered work material. Fairly uniform tensile strength and flexural load were obtained after different weld lengths for AA6061-T6 FSW joints prepared with the AlTiN coated TIF tool pin.

Decentralized Path Planning for Multi-Objective Robot Swarm System

The multi-robot path planning aims to explore a set of non-colliding paths with the shortest sum of lengths for multiple robots. The most popular approach is to artificially decompose the map into discrete small grids before applying heuristic algorithms. To solve the path planning in continuous environments, we propose a decentralized two-stage algorithm to solve the path-planning problem, where the obstacle and inter-robot collisions are both considered. In the first stage, an obstacle- avoidance path-planning problem is mathematically developed by minimizing the travel length of each robot. Specifically, the obstacle-avoidance trajectories are generated by approximating the obstacles as convex-concave constraints. In the second stage, with the given trajectories, we formulate a quadratic programming (QP) problem for velocity control using the control barrier and Lyapunov function (CBF-CLF). In this way, the multi-robot collision avoidance as well as time efficiency are satisfied by adapting the velocities of robots. In sharp contrast to the conventional heuristic methods, path length, smoothness and safety are fully considered by mathematically formulating the optimization problems in continuous environments. Extensive experiments as well as computer simulations are conducted to validate the effectiveness of the proposed path-planning algorithm.

Connectivity and Timing Assessment of Public Transport System in Diverse Scenario in an Urban City Using Geo-Spatial Techniques

Abstract: In modern context the connectivity of transport system is very important and necessary in an urban and smart city. Due to more population and more vehicles in an urban city, it is not very easy to travel from one location to another location in smooth manner. Availability of different kind of transport mediums like metro, buses, auto, ola, uber etc. helps in travelling within the city by covering different locations. Metro is considered as the primarily best and easy medium for travelling with least congestion and stoppage points. After metro, bus and auto are the secondary public transport medium having frequently used by public on daily basis. Other private transit modes are also available like Ola, Uber and Rapido, who charge according to the travel length, journey time and availability of their service in that area. But if we compare all of them in terms of availability, reliability, speed and smoothness, metro is taken as best and safe way to travel without any hesitation. The connectivity of Lucknow city which is the capital of Uttar Pradesh, India, is having good connectivity in terms of metro and bus medium. But beside metro, due to lack of infrastructure and good management it is sometimes difficult to move from one part of the city to another part by other public transport system. This study will assess the different parameters of public transport system and it will provide the correlation between them. Keywords: Connectivity, Reliability, Infrastructure, Smart City, Smoothness, Transport System.

Super-thin ALT flap elevation using preoperative color doppler ultrasound planning: Identification of horizontally running pathway at the deep adipofascial layers

Presently, super-thin ALT flap, which is elevated above the superficial fascial plane, is gaining popularity. Although there is a huge demand for thin flaps for various types of extremity reconstruction, the technique for ALT flap thinning remains controversial. In this study, we investigated the distance and vector between penetrating points of perforators in deep and superficial fascia using color duplex and clinical measurement to suggest a reliable super-thin flap elevation technique. From June 2018 to February 2020, 44 patients with various types of defects who were treated using super-thin ALT flaps were enrolled; 69 surgically detected perforators were analyzed. All patients' flap outcomes and characteristics of the perforators were analyzed. In addition, the effects of patients' body mass index (BMI) and thickness of super-thin flap were evaluated. The average traveling length of perforator at the deep adipofascial layer (DAL) was 2.43cm, and the vector of traveling was randomly arranged. The mean thickness of super-thin ALT flap was 6.8mm. The thickness of super-thin flap was not significantly correlated with patients' BMI (ranged from 17.4 to 34.2kg/m2; p=0.183). The novel elevation technique for super-thin ALT might be useful, as evidenced by perforator traveling distance and vector in DAL. Preoperative color duplex ultrasonography is helpful to detect the running course of the perforators during elevating the flap. This anatomic concept must be considered to obtain the reliability of the super-thin ALT flap.