Modelling runoff generation and connectivity for semi-arid hillslopes and small catchments

The processes relating to runoff generation in a semi-arid environment at the hillslope scale are poorly understood. This research considers the amount and origin of water reaching the channel during a storm event using a combination of field experiments and computer simulation techniques. From the field experiments, it was found that the key controls on runoff generation at the point scale are the surface cover of rock fragments, vegetation cover, slope gradient and surface roughness. The effect of land management was found to be greater than geology. The simulation modelling work investigated the controls on runoff generation at the hillslope and small catchment scales. It was found that the storm characteristics are far more important than surface properties in determining the amount of discharge from a slope. The temporal fragmentation of the rainfall was found to control the distribution of flow path lengths and hence the amount of discharge leaving a slope. The key surface controls on the form of the discharge hydrograph are slope length, slope gradient and the hydrological properties at the base of the slope. The origin of runoff was investigated using autonomous software agents able to trace the flow of water through a catchment. This technique is able to give a unique picture of the origin of runoff within a catchment. It was shown that the spatial pattern of the origin of runoff is complex and varies significantly between catchments. This research has shown that there are two key themes in determining the amount of runoff reaching the channel network: the interplay between the distribution of flow path lengths generated during a storm and the distributions of flow lengths to the channel as a function of the landscape. The second theme relates to the importance of the spatial structure of hydrological areas within the landscape

Integrability of Large-Charge Sectors in Generic 2D EFTs

It is shown that integrability is an accidental property of generic two-dimensional $O(2)$-symmetric asymptotically-free theories in the regime where the charge density is much larger than the dynamical scale. We show this by constructing an infinite tower of higher-spin conserved currents in the most generic effective Lagrangian at large chemical potential to all orders in perturbative expansion in the renormalization-group invariant coupling constant.Comment: 8 page

Minimization of Active Transmission Loss in Power Systems using Static Var Compensator

Increasing demand for electrical power as a result of modern civilization has imposed challenges such as voltage instability, transmission loss, and power factor fluctuations on power systems. In an attempt to overcome these challenges, FACTS devices are employed. This paper presented the application of Static Var Compensator to the Nigerian 330kV Power Network to study its effect on the system’s active transmission loss. SIMULINK/MATLAB was used to model the Nigerian 330kV Power Network and the SVC. The simulation result showed that by applying the Static Var Compensator, the systems total active transmission loss was reduced by 31.79%. From the above percentage reduction and the pattern of the associated chart and graph, it was observed that SVC could be used for active transmission loss minimization in power systems

ORE User Guide - Resource Map Implementation in JSON-LD 0.9

Open Archives Initiative Object Reuse and Exchange (OAI-ORE) defines standards for the description and exchange of aggregations of Web resources. OAI-ORE introduces the notion of a Resource Map, an RDF Graph which describes the Aggregation, the aggregated Resources of which it is composed, and the relationships between them (and/or the relationships between these and other resources). Since a Resource Map is an RDF Graph, it can be serialized using any RDF syntax. This document outlines the use of one such syntax for the serialization of Resource Maps: JSON-LD. This document is intended for implementers who have an understanding of ORE concepts and are responsible for the development of applications which generate or process Resource Maps using JSON-LD.This document is available at http://www.openarchives.org/ore/0.9/jsonl

Development of a web-based single-phase load monitoring and auditing system

In a developing nation like Nigeria, the conventional load monitoring and billing system has proved to be tedious, time-consuming, expensive, and prone to human error over the years. Therefore, this creates the need for an efficient system that can assist the Utility to monitor the energy consumption trend of the customers remotely. This work developed a web-based single-phase load monitoring and auditing system using NodeMCU (ESP8266) microcontroller, PZEM-004T sensor, and liquid crystal display (LCD) module for the hardware unit and Blynk internet of things (IoT) platform for the software unit. The system design was implemented around the ESP8266 microcontroller with relevant design models, and standard power and energy equations programmed into the microcontroller in the Arduino integrated development environment. The developed system was load tested to examine its performance and determine its reading error. The hardware and software units of the system operated satisfactorily when tested. The reading accuracy for current and voltage measured by the device were ±0.2% and ±0.4%, respectively, giving a reading error of ±0.8% for power measurement. The developed system is suitable for residential, commercial, and similar applications where the energy usage trend of some small loads is required for management purposes

Optimizing persistent currents in a ring-shaped Bose-Einstein condensate using machine learning

We demonstrate a method for generating persistent currents in Bose-Einstein condensates by using a Gaussian process learner to experimentally control the stirring of the superfluid. The learner optimizes four different outcomes of the stirring process: (O.I) targeting and (O.II) maximization of the persistent current winding number; and (O.III) targeting and (O.IV) maximization with time constraints. The learner optimizations are determined based on the achieved winding number and the number of spurious vortices introduced by stirring. We find that the learner is successful in optimizing the stirring protocols, although the optimal stirring profiles vary significantly depending strongly on the choice of cost function and scenario. These results suggest that stirring is robust and persistent currents can be reliably generated through a variety of stirring approaches.Comment: 11 pages, 8 figures, 1 tabl

Power System’s Voltage Stability Improvement Using Static Var Compensator

In alternating current systems, voltage fluctuation is a common phenomenon. Most of the voltage fluctuation problems result from the changes in the system’s reactive power resulting from excessive supply or consumption of reactive power by the elements of the system and the variation in the consumers’ loads. In this paper, the effect of Static Var Compensator (SVC) in stabilizing power system’s voltage through effective reactive power compensation was investigated. Power flow equations involving voltage drop with/without SVC were developed. SVC modeling equations were also developed and used to determine its parameters. Based on the SVC parameters, SIMULINK blocks were used to implement the phase controlled Thyristor–Controlled-Reactor Fixed-Capacitor (TCR-FC) SVC. The Nigerian 28-bus power system used for the study was also modeled using SIMULINK/MATLAB. The 28-bus system was first simulated without SVC and then with two SVCs located at different buses to obtain the bus voltages in both cases. From the bus voltages the total voltage drops for the system with and without SVC were estimated and compared. The compared results clearly showed that, the system’s voltage drop was reduced by 33.78% indicating a significant improvement in the system’s voltage stability when SVCs were applied

The quality of service of the deployed LTE technology by mobile network operators in Abuja-Nigeria

In this study, the real-world performance analysis of four Nigerian mobile network operators (MNOs), namely MTN, GLO, Airtel, and 9Mobile long-term evolution (LTE) cellular network, were analyzed and compared. The Nigerian MNOs utilize 5 MHz, 10 MH, and 20 MHz channel bandwidths based on third-generation partnership project’s (3 GPPs) recommendation. The presented analysis shows the uplink (UL), and downlink (DL) throughputs gaps in mobility condition as well as other LTE’s system quality of service (QoS) key performance indicators (KPI’s) of: Connection drop rate, connection failure rate, peak physical downlink throughput, minimum radio link control (RLC) downlink throughput threshold and latency are not strictly followed. The reason may be due to a lack of regulatory oversight enforcement. The comparative studies showed that MTN provides the best QoS. The introduction of novel LTE QoS metrics herein referred to as national independent wireless broadband quality reporting (NIWBQR) is the significant contribution of this study. The goal of this study is to show the quality of the network as it affects the user's experience. Important observation showed that all the MNOs are not adhering to the 3 GPPs specified user plane latency of 30 ms and control plane latency of 100 ms, respectively, which makes video streaming and low latency communication a near-impossible task