9,986 research outputs found

    Cities as emergent models: the morphological logic of Manhattan and Barcelona

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    This paper is set to unveil several particulars about the logic embedded in the diachronic model of city growth and the rules which govern the emergence of urban spaces. The paper outlines an attempt to detect and define the generative rules of a growing urban structure by means of evaluation techniques. The initial approach in this regards will be to study the evolution of existing urban regions or cities which in our case are Manhattan and Barcelona and investigate the rules and causes of their emergence and growth. The paper will concentrate on the spatial aspect of the generative rules and investigate their behaviour and dimensionality. Several Space Syntax evaluation methods will be implemented to capture the change of spatial configurations within the growing urban structures. In addition, certain spatial elements will be isolated and tested aiming to illustrate their influence on the main spatial structures. Both urban regions were found to be emergent products of a bottom up organic growth mostly distinguished in the vicinities of the first settlements. Despite the imposition of a uniform grid on both cities in later stages of their development these cities managed to deform the regularity in the preplanned grid in an emergent manner to end up with an efficient model embodied in their current spatial arrangement. The paper reveals several consistencies in the spatial morphology of both urban regions and provides explanation of these regularities in an approach to extract the underlying rules which contributed to the growth optimization process

    European social workers in England: exploring international labour mobility

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    Social work is generally regarded as an essentially ‘local activity’ but it is increasingly acknowledged that European and international trends have a bearing on development of national services and practices. This extends to the mobility of social workers themselves and England has experienced a steady growth in the recruitment of ‘international social workers’ who were born and qualified elsewhere. This is a generally under-researched area but the authors have drawn on literature in the wider field of labour migration and also secondary data and anecdotal evidence to present some facts and ideas about recruitment as it applies to social workers from European Union (EU) member states in particular. International social workers come to England from a large number and wide range of countries. However, the balance has been shifting between recruitment predominantly from the US and Commonwealth countries to a greater number from EU states. The current characteristics of international (particularly EU) social work recruitment are outlined in this paper and reasons related to both (national) demand and (international) supply are suggested. It is proposed that reasons are related to changes and conditions in the EU; to the national Government’s efforts to curb immigration; and to the particular characteristics of social work employment in England, particularly in child protection work. Some of the implications for European social workers of working in England are explored and it is concluded that there is a need for comparative and transnational research in this field

    Reduction of the phase jitter in differential phase-shift-keying soliton transmission systems by in-line Butterworth filters

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    We examine reduction of phase jitter by use of in-line Butterworth filters in soliton systems in the context of differential phase-shift-keying coding. We also demonstrate numerically that the use of a Butterworth filter in a return-to-zero differential phase-shift-keying system can reduce continuum background radiation

    Modelling The Spatial Morphogenesis In Cities: The Dynamics of Spatial Change in Manhattan

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    Applied studies in the area of urban growth have often focused on the apparent physical silhouette of urban form in modelling and simulating city growth. This paper is intended to go beyond such limitations and present a model based on observed dynamics of change in urban structures. Thus the paper translates the spatial laws which govern the process of urban morphogenesis in cities into mathematical rules which represent the change in the configurational structure of street networks. For this purpose, a set of analyses will be made for the sequential development of urban street network in Manhattan. The change in the attributes of the elements under investigation will be judged according to physical and angular metrics. The objectives are to track any regularity in the bottom up growing system and detect the causal forces that took part in the rise of a distinguished structure in the planned uniform grid. The externalised model has the potential to be devised in computer aided design implementations and strategic planning development

    Erbium-doped fiber amplifier elements for structural analysis sensors

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    The use of erbium-doped fiber amplifiers (EDFA's) in optical fiber sensor systems for structural analysis is described. EDFA's were developed for primary applications as periodic regenerator amplifiers in long-distance fiber-based communication systems. Their in-line amplification performance also makes them attractive for optical fiber sensor systems which require long effective lengths or the synthesis of special length-dependent signal processing functions. Sensor geometries incorporating EDFA's in recirculating and multiple loop sensors are discussed. Noise and polarization birefringence are also considered, and the experimental development of system components is discussed

    Diagrammatic analysis of the two-state quantum Hall system with chiral invariance

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    The quantum Hall system in the lowest Landau level with Zeeman term is studied by a two-state model, which has a chiral invariance. Using a diagrammatic analysis, we examine this two-state model with random impurity scattering, and find the exact value of the conductivity at the Zeeman energy E=ΔE = \Delta. We further study the conductivity at the another extended state E=E1E = E_1 (E1>Δ E_1 > \Delta). We find that the values of the conductivities at E=0E = 0 and E=E1E = E_1 do not depend upon the value of the Zeeman energy Δ\Delta. We discuss also the case where the Zeeman energy Δ\Delta becomes a random field.Comment: 14P, Late

    Android Malware Clustering through Malicious Payload Mining

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    Clustering has been well studied for desktop malware analysis as an effective triage method. Conventional similarity-based clustering techniques, however, cannot be immediately applied to Android malware analysis due to the excessive use of third-party libraries in Android application development and the widespread use of repackaging in malware development. We design and implement an Android malware clustering system through iterative mining of malicious payload and checking whether malware samples share the same version of malicious payload. Our system utilizes a hierarchical clustering technique and an efficient bit-vector format to represent Android apps. Experimental results demonstrate that our clustering approach achieves precision of 0.90 and recall of 0.75 for Android Genome malware dataset, and average precision of 0.98 and recall of 0.96 with respect to manually verified ground-truth.Comment: Proceedings of the 20th International Symposium on Research in Attacks, Intrusions and Defenses (RAID 2017

    Report and Reflections from Year One of the NSF GK- 12 Program at USM

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