Ductile mandrel and parting compound facilitate tube drawing

Refractory tubing is warm drawn over a solid ductile mandrel with a powder parting compound packed between mandrel and the tubes inner surface. This method applies also to the coextrusion of a billet and a ductile mandrel

Urban and Rural—Population and Energy Consumption Dynamics in Local Authorities within England and Wales

The formulation of feasible and pragmatic policies that mitigate climate change would require a thorough understanding of the interconnectivity that exists between environment, energy, and the composition of our settlements both urban and rural. This study explores the patterns of energy consumption in England and Wales by investigating consumption behavior within domestic and transport sectors as a function of city characteristics, such as population, density, and density distribution for 346 Local Authority Units (LAU). Patterns observed linking energetic behavior of these LAUs to their respective population and area characteristics highlight some distinctly contrasting consumption behaviors within urban and rural zones. This provides an overview of the correlation between urban/rural status, population, and energy consumption and highlights points of interest for further research and policy intervention. The findings show that energy consumption across cities follows common power law scaling increasing sub-linearly with their population regardless of their urban/rural classification. However, when considering per capita and sector specific consumptions, decreasing per capita consumption patterns are observed for growing population densities within more uniformly populated urban LAUs. This is while rural and sparsely populated LAUs exhibit sharply different patterns for gas, electricity, and transport per capita consumption

Productivity, infrastructure, and urban density – an allometric comparison of three European city-regions across scales

Agglomeration-based arguments citing Dutch and German city-regions have been a primary driver in advocating intercity transport strategies in the north of England. In this paper, we adopt an allometric urban model investigating the applicability and transferability of these transport-led agglomerative strategies promoted to address England’s regional economic under-performance. This is undertaken through a comparative study of the size-cost performance balance of three city-regions and the overall urban networks in the Netherlands, Germany, and England and Wales using city units defined at different spatial scales. While our results support a case for better mobility and transport comparing the three urban networks regardless of the spatial scales, comparisons of specific city-regions indicate a more nuanced interplay of productivity, mobility infrastructure, and urban density

Requirements for the spatial storage effect are weakly evident for common species in natural annual plant assemblages

Coexistence in spatially varying environments is theorised to be promoted by a variety of mechanisms including the spatial storage effect. The spatial storage effect promotes coexistence when: (i) species have unique vital rate responses to their spatial environment and, when abundant, (ii) experience stronger competition in the environmental patches where they perform better. In a naturally occurring southwest Western Australian annual plant system we conducted a neighbour removal experiment involving eleven focal species growing in high-abundance populations. Specifically, we measured species' fecundity across a variety of environmental gradients in both the presence and absence of neighbours. For the environmental variables that we measured, there was only limited evidence for species-specific responses to the environment, with a composite variable describing overstory cover and leaf litter cover being the best predictor of fecundity for a subset of focal species. In addition, although we found strong evidence for intra-specific competition, positive environment-competition covariance was only detected for one species. Thus, positive environment-competition covariance may not be as common as expected in populations of species growing at high abundance, at least when tested in natural assemblages. Our findings highlight the inherent limitations of using natural assemblages to study spatial coexistence mechanisms, and we urge empirical ecologists to take these limitations into account when designing future experiments

On the use of random graphs in analysing resource utilization in urban systems

Urban resource models increasingly rely on implicit network formulations. Resource consumption behaviours documented in the existing empirical studies are ultimately by-products of the network abstractions underlying these models. Here, we present an analytical formulation and examination of a generic demand-driven network model that accounts for the effectiveness of resource utilization and its implications for policy levers in addressing resource management in cities. We establish simple limiting boundaries to systems' resource effectiveness. These limits are found not to be a function of system size and to be simply determined by the system's average ability to maintain resource quality through its transformation processes. We also show that resource utilization in itself does not enjoy considerable size efficiencies with larger and more diverse systems only offering increased chances of finding matching demand and supply between existing sectors in the system

Comment on Bettignies et al. The scale-dependent behaviour of cities: a cross-cities multiscale driver analysis of urban energy use. Sustainability 2019, 11, 3246

Bettignies et al. examine power-law relationships between drivers of energy use and urban features at city and infra-city levels for ten different cities in six countries across four continents, featuring a wide distribution of urban indicators from various data sources. The authors employ univariate linear regression models using selected log-transformed indicators to investigate whether the intensity of energy use scales with urban indicators such as population size, density, and income. Bettignies et al. suggest that based on their findings, the urban energy-use drivers are in fact scale-dependent, and that their results reveal a substantial heterogeneity across and within cities. They reference this as why more consideration needs to be paid to local factors when devising urban policy. On this note, we argue that Bettignies et al. appear to have not only misunderstood the urban scaling literature they have cited, but have also employed flawed methodological design in their analysis that ultimately leaves their conclusions unsubstantiated

Deep multimodal learning for residential building energy prediction

The residential sector has become the second-largest energy consumer since 1987 in the UK. Approximately 24 million existing dwellings in England made up over 32% of the overall energy consumption in 2020. A robust understanding of existing buildings' energy performance is therefore critical in guiding proper home retrofit measures to accelerate towards meeting the UK's climate targets. A substantial number of predictions at a city scale rely on available data, e.g., Energy Performance Certificates (EPCs) and GIS products, to develop statistical and machine learning models to estimate energy consumption. However, issues with existing data are not negligible. This work adopted the idea of deep multimodal learning to study the potential for using Google Street View (GSV) images as an additional input for residential building energy prediction. 20,031 GSV images of 5,933 residential buildings in central Barnsley, UK, have been selected for a case study. All images were pre-processed using a state-of-the-art object detection algorithm to minimise the noise caused by other elements that may appear nearby. Building specifications that cannot be easily determined by the appearance are extracted from existing EPC information as text-based inputs for prediction. A multimodal model was designed to jointly take images and texts as inputs. These inputs are first propagated through a convolutional neural network and multi-layer perceptron, respectively, before being combined into a connected network for final energy prediction. The multi-input model was trained and tested on the case study area and predicted an annual energy consumption with a mean absolute difference of 0.01kWh/m2 per annum on average compared with what is recorded in the EPC. The difference between the predicted results and the EPC may also provide some hints on the bias the certificates potentially contain

Sorting Permutations: Games, Genomes, and Cycles

Permutation sorting, one of the fundamental steps in pre-processing data for the efficient application of other algorithms, has a long history in mathematical research literature and has numerous applications. Two special-purpose sorting operations are considered in this paper: context directed swap, abbreviated cds, and context directed reversal, abbreviated cdr. These are special cases of sorting operations that were studied in prior work on permutation sorting. Moreover, cds and cdr have been postulated to model molecular sorting events that occur in the genome maintenance program of certain species of single-celled organisms called ciliates. This paper investigates mathematical aspects of these two sorting operations. The main result of this paper is a generalization of previously discovered characterizations of cds-sortability of a permutation. The combinatorial structure underlying this generalization suggests natural combinatorial two-player games. These games are the main mathematical innovation of this paper.Comment: to appear in Discrete Mathematics, Algorithms and Application

Non-cooperative game based congestion control for data rate optimization in vehicular ad hoc networks

The growth of connected vehicles in smart cities increases the number of information being communicated on the Internet of Vehicle networks. This causes wireless channel congestion problems, which degrades the network performance and reliability due to the low throughput, high average delay and the high packets loss. Therefore, this paper proposes a non-cooperative game approach to control congestion in the vehicular ad-hoc network channel where the nodes behave as selfish players requesting high data transmission rates. Moreover, the satisfaction of the Nash equilibrium condition for the optimum data transmission rate for each vehicle, is proven. A utility function is introduced based on data transmission rates, the priority of vehicles and contention delay in order to obtain the optimal rates. The performance of the proposed approach has been evaluated and validated in comparison with three others approaches over two testing scenarios for highway and urban traffic. The results show that the network performance and efficiency have been improved by an overall average of 35%, 30% and 37.17% in terms of packets loss, channel busy time and number of collision messages, respectively, as compared with the state-of-the-art-strategies for the highway testing scenario. Similar performance is achieved for the urban testing scenario. Keywords: Vehicular ad hoc networks, Congestion control, Non-cooperative game approach, Data rate adaptation, IoV applications