Road Clearance Research Articles

Active Variable Reactance Rectifier—A New Approach to Compensating for Coupling Variations in Wireless Power Transfer Systems

This article introduces a new approach to compensate for coupling variations in wireless power transfer (WPT) systems by utilizing an active variable reactance (AVR) rectifier. The AVR rectifier operates at a fixed frequency and incorporates a power-splitting resonant network. By controlling the ratio of the split powers in its branches, the AVR rectifier continuously compensates for large misalignments and distance variations between couplers, while maintaining full power transfer. A comprehensive methodology is presented that maximizes the tolerable range of misalignments in an AVR-rectifier-enabled capacitive WPT system while meeting efficiency targets. The proposed approach is validated using a 13.56-MHz, 300-W, 12-cm nominal air-gap prototype capacitive WPT system, which incorporates an AVR rectifier and can be scaled up in power for dynamic electric vehicle (EV) charging applications. The prototype system maintains full power transfer for up to 45% lateral misalignment in the coupler and up to 45% increase in the vehicle's road clearance. In a dynamic EV charging scenario, the AVR-rectifier-enabled system transfers 80% more energy during a single pass of the vehicle over the charging pad, as compared to a system without the AVR rectifier. The measured performance of the prototype system is in good agreement with predictions.

A distributed approach for road clearance with multi-robot in urban search and rescue environment

In urban search and rescue domains, robots explore the affected terrain to search and assist disaster victims. RoboCup Rescue simulation provides a platform for disaster management where heterogeneous field agents (fire-brigade agent, ambulance agent, and police force agent) collaborate to manage a mimicked calamity situation. The role of police force agents is crucial, as they clear the blocked roads to allow other agents to perform their tasks. In this paper we suggest a distributed multi-robot coordination approach for clearing a road blocked with heavy obstacles. The proposed framework is implemented and simulated in ARGoS, a multi-robot simulator. The experimental results show the validity and satisfactory performance of the proposed approach.

Reducing vehicle-related NOx and PM emissions in metropolitan areas

With scientific discoveries indicating a relationship between nitrogen oxides/particulate matter and cancers/heart disease, and the growing road transport sector in Western Europe, there is an increasing urgency to further reduce vehicle emissions. This comprises a large part of the total emissions in urban areas. In this article, we address the question of how various local policy instruments and technology can be used to support the use of clean road vehicles in urban areas. Despite some moderate success in specific areas, local policies and technology need to become even more effective. Using the STREAMS model, a comparative analysis is made of six urban cases in the Randstad and the Rhine-Ruhr metropolitan areas. The study provides new insights into the dynamics between the perceived problems, policy making (in terms of the adoption of policy instruments), politics (in terms of the fit/misfit between stakeholders’ interests, which may result in a window for policy change), and technology. The policy instruments examined include low emission zones, parking licence restrictions, and incentives to adopt electric vehicles. Policy recommendations are made regarding effective policy instruments for the reduction of harmful emissions in metropolitan areas. Implications for theory are also discussed.

Reducing vehicle-related NOx and PM emissions in metropolitan areas: A comparison between the Randstad and the Rhine-Ruhr area

Abstract With scientific discoveries indicating a relationship between nitrogen oxides/particulate matter and cancers/heart disease, and the growing road transport sector in Western Europe, there is an increasing urgency to further reduce vehicle emissions. This comprises a large part of the total emissions in urban areas. In this article, we address the question of how various local policy instruments and technology can be used to support the use of clean road vehicles in urban areas. Despite some moderate success in specific areas, local policies and technology need to become even more effective. Using the STREAMS model, a comparative analysis is made of six urban cases in the Randstad and the Rhine-Ruhr metropolitan areas. The study provides new insights into the dynamics between the perceived problems, policy making (in terms of the adoption of policy instruments), politics (in terms of the fit/misfit between stakeholders’ interests, which may result in a window for policy change), and technology. The policy instruments examined include low emission zones, parking licence restrictions, and incentives to adopt electric vehicles. Policy recommendations are made regarding effective policy instruments for the reduction of harmful emissions in metropolitan areas. Implications for theory are also discussed.

Minimizing latency in post-disaster road clearance operations

After a natural disaster, roads and bridges can be damaged or blocked by debris, causing inaccessibility between critical locations such as hospitals, disaster response centers, shelters and disaster-struck areas. We study the post-disaster road clearing problem with the aim of providing a fast and effective method to determine the route of a work troop responsible for clearing blocked roads. The problem is to find a route for the troop that starts at the depot and visits all of the critical locations. The objective is to minimize the total latency of critical nodes, where the latency of a node is defined as the travel time from the depot to that node. A mathematical model for this problem has already been developed in the literature. However, for real-life instances with more than seven critical nodes, this exact formulation cannot solve the problem optimally in a 3-hour limit. To find a near-optimal solution in a short running time, we develop a heuristic that solves a mixed integer program on a transformed network and a lower bounding method to evaluate the optimality gaps. Alternatively, we develop a metaheuristic based on a combination of Greedy Randomized Adaptive Search Procedure (GRASP) and Variable Neighborhood Search (VNS). We test both the matheuristic and the metaheuristic on Istanbul data and show that optimal or near-optimal solutions are obtained within seconds. We also compare our algorithms with existing work in the literature. Finally, we conduct an analysis to observe the trade-off between total and maximum latency.

An assessment of the inhalation bioaccessibility of platinum group elements in road dust using a simulated lung fluid

Metal enrichment of road dust is well characterized but available data on the bioaccessibility of metals in particle size fractions relevant to human respiratory health remain limited. The study goal was to investigate the bioaccessibility of platinum group elements (PGE), which are used as catalysts in automotive exhaust converters, in the inhalable fraction of road dust. Street sweepings were provided by the City of Toronto, Canada, collected as part of its Clean Roads to Clean Air program.The particle size relevance of road dust for inhalation exposures was confirmed using a laser diffraction particle size analyzer (mean Dx(50): 9.42 μm). Total PGE were determined in both bulk and inhalable fractions using nickel sulfide (NiS) fire-assay and instrumental neutron-activation analysis (INAA). PGE lung solubility was examined for the inhalable fraction using Gamble’s extraction. Sample digests were co-precipitated with Te-Sn, to pre-concentrate and isolate PGE, prior to their measurement using inductively coupled plasma mass spectrometry (ICP-MS).Total PGE concentrations were enriched in the inhalable fraction of road sweepings. Geomean concentrations in the inhalable fraction were: palladium (Pd) (152 μg/kg), platinum (Pt) (55 μg/kg), rhodium (Rh) (21 μg/kg) and iridium (Ir) (0.23 μg/kg). Osmium (Os) concentrations were below the limit of detection (LOD). Bioaccessible PGEs (n = 16) using Gamble’s solution were below LOD for Ir and ruthenium (Ru). For the remainder, the geomean % bioaccessibility was highest for platinum (16%), followed by rhodium (14%) and palladium (3.4%). This study provides evidence that PGE in road dust are bioaccessible in the human lung.

Revascularization Techniques for Acute Basilar Artery Occlusion : Technical Considerations and Outcome in the Setting of Severe Posterior Circulation Steno-Occlusive Disease.

To describe the clinical and radiological characteristics, frequency, technical aspects and outcome of endovascular treatment of acute basilar artery occlusion (ABO) in the setting of vertebrobasilar steno-occlusive disease. Retrospective analysis of databases of two universitary stroke centers including all consecutive patients from January 2013 until May 2017 undergoing thrombectomy for a) acute stroke due to basilar artery occlusion and either significant basilar artery stenosis or vertebral artery stenosis/occlusion as well as b) presumed embolic basilar artery occlusions. Demographics, stroke characteristics, time metrics, recanalization results and outcome were recorded. Interventional strategies were evaluated concerning the thrombectomy technique, additional angioplasty, type of approach with respect to lesion pattern (ipsilateral to steno-occlusive VA lesion: dirty road or contralateral: clean road) and sequence of actions. Out of 157 patients treated for ABO 38 (24.2%) had associated significant vertebrobasilar steno-occlusive lesions. An underlying significant basilar artery stenosis was present in 23.7% and additionally significant steno-occlusive vertebral lesions were present in 81.5%. Thrombectomy was performed with primary aspiration in 15.8% and with stent-retrievers in 84.2%. Successful revascularization (TICI 2b-3) was achieved in 86.8%. In 52.6% additional stent angioplasty was performed, in 7.9% balloon angioplasty only. The clean road approach was used in 22.5% of cases, the dirty road in 77.4%. Final modified Rankin scale (mRS) was 0-2 in 6patients (15.8%) and 3-5 in 32 (84.2%). The in-hospital mortality was 36.8%. There were no statistically significant differences in outcome compared to presumed cases of embolisms. Endovascular treatment of ABO with underlying significant vertebrobasilar steno-occlusive lesions is effective and reasonably safe. Specific procedural strategies apply depending on individual patient pathology and anatomy. Although high rates of recanalization can be achieved, outcomes tend to be poor.

Real-time prediction and avoidance of secondary crashes under unexpected traffic congestion

According to the Federal Highway Administration, nonrecurring congestion contributes to nearly half of the overall congestion. Temporal disruptions impact the effective use of the complete roadway, due to speed reduction and rubbernecking resulting from primary incidents that in turn provoke secondary incidents. There is an additional reduction of discharge flow caused by secondary incident that significantly increases total delay. Therefore, it is important to sequentially predict the probability of secondary incidents and develop appropriate countermeasures to reduce the associated risk. Advanced computing techniques were used to easily understand and reliably predict secondary incident occurrences that have low sample mean and a small sample size. The likelihood of a secondary incident was sequentially predicted from the point of incident response to the eventual road clearance. The quality of predictions improved with the availability of additional information. The prediction performance of the principled Bayesian learning approach to neural networks (bnn) was compared to the Stochastic Gradient Boosted Decision Trees (gbdt). A pedagogical rule extraction approach, trepan, which extracts comprehensible rules from the neural networks, improved the ability to understand secondary incidents in a simplified manner. With an acceptable accuracy, gbdt is a useful tool that presents the relative importance of the predictor variables. Unexpected traffic congestion incurred by an incident is a dominant causative factor for the occurrence of secondary incidents at different stages of incident clearance. This symbolic description represents a series of decisions that may assist emergency operators by improving their decision-making capabilities. Analyzing causes and effects of traffic incidents helps traffic operators develop incident-specific strategic plans for prompt emergency response and clearance. Application of the model in connected vehicle environments will help drivers receive proactive corrective feedback before a crash. The proposed methodology can be used to alert drivers about potential highway conditions and may increase the drivers’ awareness of potential events when no rerouting is possible, optimal or otherwise.

Coordinate Reference Frame Technique for Robotic Planar Path Planning

A Robot is swiftly advancing from workshop entity, which is objectively bound to its work cell, to a growingly intricate machine competent of doing demanding jobs in our day-to-day environment. A mobile robot which initially used for surveillance, reconnaissance and patrolling, extended its footprint in the areas of explosive devices handling, mine laying, communications relays, logistics transportation, convoy protection, road clearance, target identification and tracking, remotely operated weapons, disaster management, hospitality sector, home automation, driverless cars etc. This mobility is hugely dependent on the autonomy of the robot. Autonomous Mobile Robot (AMR) is one which is capable of traveling an uncontrolled arena without the supervision of the operator. Diverse approaches like vision-based techniques, fuzzy logic, artificial neural mapping, reactive navigation techniques, biologically inspired techniques, geometrical path planning etc. are used individually or combined to find the collision-free path. This paper discusses a new geometrical method called as Coordinate Reference Frame (CRF) approach for the navigation of mobile robot operating in a static environment consisting of elliptical obstacles. A mathematical formulation has been developed to obtain these paths and Center of Gravity Approach (CGA) is used to find the shortest among all obtained paths. The simulation results were implemented with an experiment. The results prove that the proposed approach to be very effective as the robot navigates to the defined target point without colliding with the obstacles in the arena. The cost involved in this project is very minimal, which makes this robot suitable for industries, hospitals, hotels, offices, etc. These kind of robots are very suitable for home robots, transportation robots, service robots, etc.

МОРФОФУНКЦІОНАЛЬНА ПЕРЕБУДОВА ВЕНОЗНОГО РУСЛА ПЕРЕДСЕРДЬ ЛЕГЕНЕВОГО СЕРЦЯ

В останні роки клініцисти та морфологи почали звертати увагу на легеневе серце. Варто зазначити, що патогенез хронічного легеневого серця складний і досить багатогранний, що значною мірою ускладнює своєчасну діагностику легеневої артеріальної гіпертензії та хронічного легеневого серця. Відомо, що вказана патологія перебігає на фоні змін тонусу венозних судин. В той же час морфофункціональні особливості венозної системи передсердь легеневого серця вивчені недостатньо.МЕТОЮ даної роботи стало дослідження морфофункціональних особливостей венозного русла передсердь легеневого серця.МАТЕРІАЛИ І МЕТОДИ. Комплексом морфологічних методів досліджені вени лівого та правого передсердь серця 19 статевозрілих свиней-самців в'єтнамської породи, які були розділені на 3-и групи. 1-а група нараховувала 6 інтактних дослідних тварин, 2-а – 8 свиней з артеріальною легеневою гіпертензією та компенсованим легеневим серцем, 3-я – 5 тварин з артеріальною легеневою гіпертензією та декомпенсацією легеневого серця. Артеріальну легеневу гіпертензію та легеневе серце моделювали шляхом виконанням правосторонньої пульмонектомії. Евтаназію дослідних тварин здійснювали кровопусканням в умовах тіопентал-натрієвого наркозу через місяць від початку експерименту. Проводили окреме зважування та планіметрію камер серця. Венозне русло частини сердець заповнювалося туш-желатиновою сумішшю через устя вінцевих артерій. З лівого та правого передсердь вирізали шматочки, які фіксували у 10 % нейтральному розчині формаліну і після відповідного проведення через етилові спирти зростаючої концентрації поміщали у парафін. Мікротомні зрізи товщиною 5-7 мкм фарбували гематоксилін-еозином, за ван-Гізон, Маллорі, Вейгертом, толуїдиновим синім. Гістологічні мікропрепарати досліджувалися за допомогою мікроскопів МБД-15 та Люмам-Р8.РЕЗУЛЬТАТИ ДОСЛІДЖЕННЯ ТА ЇХ ОБГОВОРЕННЯ. Окремим зважуванням та планіметрією камер серця встановлено, що через місяць після правосторонньої пульмонектомії зростала маса частин серця та їхні просторові характеристики з домінуванням гіпертрофії та дилатації правого шлуночка. Отримані результати свідчили про розвиток легеневого серця.Встановлено, що у пострезекційному компенсованому легеневому серці структура вен лівого та правого передсердь суттєво змінювалася. У змодельованих патологічних умовах у більшості випадків досліджувані структури розширені, переповнені кров'ю. спостерігався також перивазальний набряк, який міг здавлювати вени, звужувати просвіт та деформувати досліджувані судини. Виявлялася дистрофія гладких м'язових клітин, ендотеліоцитів та десквамація місцями останніх. Деякі ендотеліоцити та гладкі міоцити з явищами набряку, межі між ними нечіткі, частина клітин збільшена у розмірах, дистрофічно і некробіотично змінені. При декомпенсації легеневого серця описані вище структурні зміни вен були виражені у більшому ступені. Переважна більшість венозних судин розширені, переповнені форменими елементами крові, з явищами стазу, що свідчило про виражене порушення їх дренажної функції. Венули при цьому нерідко починалися у вигляді ампул, у які впадали розширені, часто повнокровні посткапіляри у вигляді китиць. Венозний застій у досліджуваних судинах призводив до посилення гіпоксії, дистрофії та некрозів кардіоміоцитів, інфільтративних та склеротичних процесів. Виявлені структурні зміни домінували у правому передседі декомпенсованого легеневого серця.ВИСНОВОК. Пострезекційна легенева гіпертензія та легеневе серце призводять до вираженої структурної перебудови венозного русла передсердь, що характеризується розширенням, повнокров′ям, деформацією просвіту венозних структур, порушенням їх венозної дренажної функції, посиленням гіпоксії та деструктивних процесів у міокарді, які домінують у правому передсерді декомпенсованого легеневого серця.

An Alaska case study: Electrical transmission

Electrical transmission lines in Alaska vary from overhead to submarine to underground installations. Analysis indicates that overhead transmission lines are the least expensive to build, ranging from $100 000 to $400 000/mile. Cost variability is influenced by pole spacing, pole heights, line ratings, river crossings, and the amount of work on energized power lines. Submarine lines and underground lines are substantially more expensive than overhead lines, ranging from less than $3 000 000 to more than $4 500 000/mile although there is some uncertainty in the datasets. When broken down by major cost components, the cost category including materials, construction, and installation comprises just over half of the total costs, with remaining costs distributed among the control system, substation, switchyard, road clearance, indirect costs, and contingencies. Operation and maintenance costs range from $2800/mile to $4200/mile, with an average of $3560/mile. Expected lifetimes are 20–30 years. In general, the transmission technology market is not as dynamic as other energy markets. Financing and initiatives to encourage interties may create bigger loads and economies of scale.

A shared control method for obstacle avoidance with mobile robots and its interaction with communication delay

Teleoperation allows human operators to safely extend themselves to remote environments that are typically difficult or dangerous to access. The remote environments are often unstructured (i.e. not having clear roads or paths to follow) and only accessible by wireless communication (introducing factors such as degraded signals and communication delay). Teleoperated driving under these conditions can result in slow operation speeds and unintended collisions with obstacles. Automating portions of the teleoperation task can help mitigate some of the negative effects of wireless communication. Shared control is used to combine inputs from the human teleoperator and automation. This work presents a new model predictive control based shared control method. We introduce a new representation for obstacle free regions that works well with unstructured robot environments and allows for an model predictive control problem formulation that can be solved rapidly. The shared control method is implemented in a robot simulator and tested with human subjects. Two user studies involving a search task with a mobile robot evaluate the effectiveness of the shared control method and explore its interaction with factors such as communication delay and input interface style. Communication delay is found to have the largest magnitude effect on performance and safety measures. Results demonstrate that the shared control method can improve both performance and safety when delays are present.

Quantitative assessment of national resilience: A case study of Mount Paektu eruption scenarios on South Korea

This study estimated South Korea's resilience to volcanic eruption scenarios by summing direct and indirect losses in industrial sectors, health damages, and costs to clean roads of volcanic ash. This resilience assessment aimed to compare eruption scenarios from a socio-economic perspective and prepare mitigation strategies. Direct losses were estimated using vulnerability functions in agriculture and interruption times in air transportation and manufacturing. Indirect losses were estimated using input–output tables on South Korea. Health damages were estimated using the unit damage cost of particulate matter studied in the European Union and the United States. Resilience assessment results depended on eruption scenarios and the locations of vulnerable items. The industrial sectors had indirect losses that were larger than direct losses, suggesting the inclusion of indirect losses in economic impact assessments of natural hazards. This study indicated that the community resilience cost index (CRCI) is useful in assessing community resilience to hazards. The CRCI quantified the economic differences in eruption scenarios, and could lead an optimal hazard mitigation to enhance resilience. The CRCI can be applied to other hazards by defining and measuring losses and recovery strategies using appropriate data and to develop mitigation strategies by defining the interaction between losses and recovery costs.

Swachh Bharat Abhiyan Clean India Abhiyan

According to the statistics, it has seen that only few percentage of total population have access to the toilets. It is a programmer run by the government to seriously work to fulfill the vision of Father of Nation (Bapu) by calling the people from all walks of life to make it successful globally. Swachh Bharat Abhiyan is a national cleanliness campaign established by the Government of India. This campaign is covering 4041 statutory towns in order to clean roads, streets, and infrastructure of the India. It is a mass movement has run to create a Clean India by 2019. It is a step ahead to the Mahatma Gandhi’s dream of Swachh Bharat for healthy and prosperous life. This mission was launched on 2nd of October 2014 (145th birth anniversary of Bapu) by targeting its completeness in 2019 on 150th birth anniversary of Bapu. The mission has been implemented to cover all the rural and urban areas of the India under the Ministry of Urban Development and the Ministry of Drinking Water and Sanitation accordingly the first cleanliness drive (on 25th of September 2014) of this mission was started by the Indian Prime Minister, Narendra Modi earlier to its launch. This mission has targeted to solve the sanitation problems as well as better waste management all over the India by creating sanitation facilities to all. Swachh Bharat mission is very necessary to run continuously in India until it gets its goal. It is very essential for the people in India to really get the feeling of physical, mental, social and intellectual well-being. It is to make living status advance in India in real means which can be started by bringing all over cleanliness. Below I have mentioned some points proving the urgent need of Swachh Bharat Abhiyan in India.

Tool-Center-Point control of the KAI manipulator using constrained QP optimization

The KAI manipulator is a four joint mobile manipulator, which will be used within the German road clearance package to investigate improvised explosive devices and ordnance from within an armored vehicle. To improve handling of the manipulator, a Tool-Center-Point (TCP) control is implemented. By using constrained quadratic optimization (cQP) it is possible to allow for the control of the manipulator within three different operating spaces. The QP is formulated to account for constraints in the joint angular rates and TCP velocities, as well as additional velocity constraints, e.g. on the movement of the center of mass of the manipulator. The proposed algorithm is able to handle redundant as well as non redundant manipulator kinematics. By using an efficient QP solver the algorithm can be used within a real-time trajectory generation scheme. The performance of the algorithm is demonstrated using simulation results and validated by measurements of the TCP control.

Work zones versus nonwork zones: Risk factors leading to rear-end and sideswipe collisions

ABSTRACTTens of thousands of vehicular collisions occur annually in work zones with nearly double the fatality risk as compared to all collisions (work zone and nonwork zone). Due to this increase in risk, this study's objective is to investigate the possible causes of work zone collisions. After reviewing previous studies, the authors examined behavioral, environmental, and roadway geometric factors to understand their influence on fatal collision type for work zones and nonwork zones. Data from the National Highway Traffic Safety Administration Fatality Analysis Reporting System database was used for years 2010 to 2012. To analyze the data, negative binomial regression and multinomial logit models were utilized. A binary probit model directly compares work zone and nonwork zone data. Results demonstrate that rear-end and sideswipe collisions are more likely to cause fatalities in work zones compared to nonwork zones. Clear conditions, daylight, and straight roads increase the likelihood of these two collision types when compared to other types such as single-vehicle collisions. These findings suggest that Intelligent Transportation Systems countermeasures (speed harmonization, vehicle-to-vehicle communications) should be investigated to encourage safer car-following and lane-changing behaviors rather than to mitigate work zone–related infrastructure challenges.

Real-time prediction of secondary incident occurrences using vehicle probe data

Effective incident management system requires quantifying non-recurring congestion and detecting a secondary incident under the negative influence of a primary incident. Previously suggested thresholds and measurement parameters provide no universal definition of a secondary incident, regardless of discussions on the topic. To solve this dilemma, we propose a Bayesian structure equation model to recognize congestion patterns for road segments using INRIX Data. An adjustment of the boxplot is applied to capture segments at the tail of the queue and at the head of the queue where secondary incidents might occur. The resulting contour plot provides temporal–spatial area under congestion to identify secondary incidents. The likelihood of classified secondary incidents are sequentially predicted from the point of incident response to the road clearance. The prediction performance of the principled Bayesian learning approach to neural networks outperforms the logistic model. The quality of predictions improve as new information (e.g. notification-arrival of response units, speed) becomes available. A pedagogical rule extraction approach will improve the ability to understand secondary incidents by extracting comprehensible rules from the neural networks. The symbolic description represents a series of decisions to assist emergency operators in their decision-making capabilities.

Text analysis in incident duration prediction

Due to the heterogeneous case-by-case nature of traffic incidents, plenty of relevant information is recorded in free flow text fields instead of constrained value fields. As a result, such text components enclose considerable richness that is invaluable for incident analysis, modeling and prediction. However, the difficulty to formally interpret such data has led to minimal consideration in previous work.In this paper, we focus on the task of incident duration prediction, more specifically on predicting clearance time, the period between incident reporting and road clearance. An accurate prediction will help traffic operators implement appropriate mitigation measures and better inform drivers about expected road blockage time.The key contribution is the introduction of topic modeling, a text analysis technique, as a tool for extracting information from incident reports in real time. We analyze a dataset of 2years of accident cases and develop a machine learning based duration prediction model that integrates textual with non-textual features. To demonstrate the value of the approach, we compare predictions with and without text analysis using several different prediction models. Models using textual features consistently outperform the others in nearly all circumstances, presenting errors up to 28% lower than models without such information.

The hydrological role of ‘sunken lanes’ with respect to sediment mobilization and delivery to watercourses with particular reference to West Sussex, southern England

Roads in general and sunken lanes (SLs) in particular play an important hydrological role in connecting areas of runoff and sediment generation with valley floors and therefore with habitation and watercourses. These connections lead to damage and pollution. The role of SLs has been neglected as an important source of runoff and sediment and in hydrological and geomorphological discussion in the literature on connectivity. Published data on the role of roads and specifically SLs are reviewed. Fluxes of runoff and sediment have been mapped in a study area during a period of serious erosion (2006–2007). Routes to watercourses and entry points to a vulnerable river are recorded. SLs are historic features often hundreds of years old. Unmetalled SLs continue to incise whereas metalled ones generally act as routes for runoff and sediment with inputs from many sources. These include field gateways, other SLs, tracks and trails (some metalled, some unmetalled), bank gullies and mass movements on SL banks, burrows and pipes in banks, and erosion of roadside verges. The proportion of sediments from these sources is unknown and area specific. Impacts and costs include muddy flooding of villages, road clearance and ecological damage to rivers due to pollution and sedimentation. The location of SLs is influenced by two factors: long-term human occupation of the landscape and soft, easily eroded geology. They are an important element in the connectivity between hillslopes and valley bottoms. They play a role in the muddy flooding of villages and increased sedimentation in rivers in areas such as Flanders, the Polish Carpathians and the study area in southern England.

Hydrogen and proton exchange membrane fuel cells for clean road transportation

In this paper the main issues related to the working of hydrogen fuel cells and their utilization in the transportation field are presented and discussed, starting from the experimental analysis of dynamic performance of a laboratory fuel cell system based on a 20 kWe H 2/air proton exchange membrane stack. The experiments were carried out on successive load steps characterized by low reactant relative pressures (15–50 kPa) and stack temperature of 310–350 K. The effect of air flow rate, hydrogen purge and membrane humidification strategy on stack output voltage was evaluated evidencing the role of different sub-systems in stack management (for reactant feeding, stack cooling, membrane humidification) and their effect on efficiency losses of the overall system. The results presented in this paper provide experimental indications about potentialities of hydrogen fuel cell systems as clean electric energy generators for automotive applications.