Throughput Maximization for Mobile Relaying Systems

This paper studies a novel mobile relaying technique, where relays of high mobility are employed to assist the communications from source to destination. By exploiting the predictable channel variations introduced by relay mobility, we study the throughput maximization problem in a mobile relaying system via dynamic rate and power allocations at the source and relay. An optimization problem is formulated for a finite time horizon, subject to an information-causality constraint, which results from the data buffering employed at the relay. It is found that the optimal power allocations across the different time slots follow a "stair-case" water filling (WF) structure, with non-increasing and non-decreasing water levels at the source and relay, respectively. For the special case where the relay moves unidirectionally from source to destination, the optimal power allocations reduce to the conventional WF with constant water levels. Numerical results show that with appropriate trajectory design, mobile relaying is able to achieve tremendous throughput gain over the conventional static relaying.Comment: submitted for possible conference publicatio

Experimental behaviour of FRP-confined large-scale curvilinearized rectangular RC columns under axial compression

Existing research has shown that strengthening through fibre-reinforced polymer (FRP) confinement is highly effective for circular columns but much less so for sTuare and rectangular columns due to the flat sides and sharp corners in the latter. Rounding the corners in the latter columns can enhance the effectiveness of confinement, but its benefit is limited. To overcome this problem, an alternative strengthening techniTue has recently been proposed by some researchers, in which the flat sides of a sTuarerectangular section are modified into slightly curved sides before FRP confinement (referred to as section curvilinearization). The resulting columns, referred to as curvilinearized sTuare rectangular columns, are much more effectively confined by an FRP jacket than the original sTuarerectangular columns with only corner rounding, and the associated column size increase is limited. While this section curvilinearization techniTue is highly attractive, there has been only very limited research on the behaviour of FRP-confined curvilinearized sTuare rectangular columns. In particular, all the existing experimental work has been limited to small-scale sTuare columns (with section widths being around or below 1 mm) under axial compression. Against the above background, a large experimental programme has been under way at The Hong Kong Polytechnic University to study the behaviour of large-scale curvilinearized RC columns under both concentric and eccentric compression. Both sTuare and rectangular columns have been considered in the experimental programme. This paper presents a systematic experimental study on the behaviour of FRP-confined curvilinearized rectangular RC columns under axial compression to study the effects of the following parameters: rise-to-span ratio of the edge profile, sectional aspect ratio and corner radius. In addition to the presentation of experimental results, two existing stress-strain models for FRP-confined concrete in these columns are assessed to reveal their limitations

Challenges of Primary Frequency Control and Benefits of Primary Frequency Response Support from Electric Vehicles

As the integration of wind generation displaces conventional plants, system inertia provided by rotating mass declines, causing concerns over system frequency stability. This paper implements an advanced stochastic scheduling model with inertia-dependent fast frequency response requirements to investigate the challenges on the primary frequency control in the future Great Britain electricity system. The results suggest that the required volume and the associated cost of primary frequency response increase significantly along with the increased capacity of wind plants. Alternative measures (e.g. electric vehicles) have been proposed to alleviate these concerns. Therefore, this paper also analyses the benefits of primary frequency response support from electric vehicles in reducing system operation cost, wind curtailment and carbon emissions

Influence of Conditional Cash Transfer on Household Economic Outcomes: Perspective of Livelihood Empowerment Against Poverty (LEAP) Beneficiaries in Builsa North District of Ghana

Abject poverty remains widespread in many parts of the world today despite the remarkable progress achieved since the Second World War. Though poverty levels in Ghana have declined in terms of hard-core poor, the decline in poverty has, however, not been geographically spread equally. Achieving poverty reduction goals in Ghana, the Livelihood Empowerment Against Poverty (LEAP) Social Grants scheme was introduced as an effective long-term response to extreme poverty among vulnerable groups. This study assessed the influence of LEAP Cash Transfer on the economic outcomes of beneficiaries in the Builsa North District of Upper East Region, Ghana. The study employed a case study design. Data was collected from 156 randomly selected respondents using qualitative questionnaires, and focused group discussions. The study found that LEAP has played a pivotal role at strengthening the economic and social fortunes of majority of vulnerable households. It has enhanced households’ ability to participate in social functions, access education/literacy as human capital asset, and access vast agricultural lands to undertake crop farming activities. The study recommends to the implementing ministry, the Ministry of Gender and its subsidiary agencies at the District level to educated beneficiaries of the CCT to believe more in their individual efforts with little support such as the cash transfer. Keywords: Conditional Cash Transfer, Household Economic Outcome, LEAP, Builsa North, Livelihood framework DOI: 10.7176/RHSS/10-14-04 Publication date:July 31st 202

Robo-Chargers: Optimal Operation and Planning of a Robotic Charging System to Alleviate Overstay

Charging infrastructure availability is a major concern for plug-in electric vehicle users. Nowadays, the limited public chargers are commonly occupied by vehicles which have already been fully charged. Such phenomenon, known as overstay, hinders other vehicles' accessibility to charging resources. In this paper, we analyze a charging facility innovation to tackle the challenge of overstay, leveraging the idea of Robo-chargers - automated chargers that can rotate in a charging station and proactively plug or unplug plug-in electric vehicles. We formalize an operation model for stations incorporating Fixed-chargers and Robo-chargers. Optimal scheduling can be solved with the recognition of the combinatorial nature of vehicle-charger assignments, charging dynamics, and customer waiting behaviors. Then, with operation model nested, we develop a planning model to guide economical investment on both types of chargers so that the total cost of ownership is minimized. In the planning phase, it further considers charging demand variances and service capacity requirements. In this paper, we provide systematic techno-economical methods to evaluate if introducing Robo-chargers is beneficial given a specific application scenario. Comprehensive sensitivity analysis based on real-world data highlights the advantages of Robo-chargers, especially in a scenario where overstay is severe. Validations also suggest the tractability of operation model and robustness of planning results for real-time application under reasonable model mismatches, uncertainties and disturbances

Wastewater Testing Shows that Pharmaceutical and Illicit Drug Use are Higher in Places where COVID-19 is More Prevalent

Wastewater testing shows that pharmaceutical and illicit drug use are higher in places were COVID-19 is more prevalent