Preliminary Study on Siltation in Pussur Navigation Channel with Regulating Structure

In view of the serious problem of siltation rate in Waterway Engineering, feasibility of the scheme is studied from the perspective of sedimentation on Pussur River of Bangladesh in this paper. Based on the analysis of the tide, sediment and topography of the waterway and numerical simulation, the characteristics of the flow movement in the project reach, the influence of the dredging channel on the flow and the siltation were analyzed. With the excavation of channel, due to the influence of dynamic changes and elevation difference, the siltation of the channel is about 0.70–1.79m/a near Inner Bar area, and is more severely in the upper section near Chalna. The implementation of the preliminary regulating structure can increase the velocity and reduce the siltation of the local section. Yet the siltation of the upstream and downstream sections may be added due to changes of flow with the structure. The further scheme should be optimized from the angle of increasing the velocity in channel and reducing the influence to upstream and downstream. The feasibility results can provide scientific basis for the design and construction departments.

Assignments to sheaves of pseudometric spaces

An assignment to a sheaf is the choice of a local section from each open set in the sheaf's base space, without regard to how these local sections are related to one another. This article explains that the consistency radius --- which quantifies the agreement between overlapping local sections in the assignment --- is a continuous map. When thresholded, the consistency radius produces the consistency filtration, which is a filtration of open covers. This article shows that the consistency filtration is a functor that transforms the structure of the sheaf and assignment into a nested set of covers in a structure-preserving way. Furthermore, this article shows that consistency filtration is robust to perturbations, establishing its validity for arbitrarily thresholded, noisy data.

CREATION OF A QUASIGEOID MODEL ON A LOCAL SECTION BY GIS MEANS

The capabilities of fully functional geographic information systems used in various fields make it possible to simulate the characteristics of the gravitational field, presenting measuring information in the form of continuous surfaces, thereby expanding the area of use of data on the Earth's gravitational field. An important stage of visualization is the choice of a method of interpolating data that provides the highest possible accuracy in creating a digital model of the studied characteristic of the gravitational field. The authors developed a technology for choosing the optimal method for interpolating the characteristics of the Earth's gravitational field in a GIS to create models with an assessment of their accuracy according to the initial data, presented in the form of a technological scheme. The possibilities of the Golden Software Surfer software product for creating a model of quasi-geoid heights from the unevenly presented satellite and geometric leveling data in the study area are considered. A method for interpolating the heights of a quasi-geoid in Golden Software Surfer is proposed, a model of a quasi-geoid in a local area is created. An assessment of the accuracy of the created model according to the initial data is performed.

From theory to engineering practice: shared telecommunications knowledge between Oliver Heaviside and his brother and GPO engineer Arthur West Heaviside

In May 1900, renowned General Post Office (GPO) engineer Arthur West Heaviside gave the Inaugural Address of the Institution of Electrical Engineers Newcastle local section. With a career spanning the pre-Telegraph Act private telegraph networks as well as the subsequent GPO management and licensing of British inland telecommunications, Arthur Heaviside outlined his innovative and experimental work with all three forms of telecommunication in his various GPO engineering roles based in Newcastle. Omitted from the address was the contribution made by Arthur's younger brother, Oliver Heaviside. Throughout Arthur's career at the GPO, the two brothers exchanged frequent correspondence—some of which has survived in the IET Archives—and Arthur regularly consulted his brother about his experimental work and published papers, incorporating his brother's ideas, suggestions and corrections. The two brothers informally collaborated and published separately upon two key areas of experimentation: duplex telegraphy and the ‘bridge system’ of telephony. The separate publication of the brothers' work in telecommunications was notable: senior and influential GPO electrical engineer William Preece strongly resisted the theoretical work of Oliver Heaviside and other so-called Maxwellians. It was not until the ‘Kennelly–Heaviside layer’, independently proposed by Oliver Heaviside and American electrical engineer Arthur Kennelly in 1902, was experimentally demonstrated in the 1920s that the GPO began to formally engage with the work of Oliver Heaviside. This paper will explore the difficult and complex relationship between Preece and the two Heaviside brothers and how these personal relationships reflect the wider reception of Maxwellian ideas and theorists in British electrical engineering as well as the engineering practice of the GPO, a state institution that could be both innovative and resistant to change in equal measure.This article is part of the theme issue ‘Celebrating 125 years of Oliver Heaviside's ‘Electromagnetic Theory’’.