Machine Learning at the Network Edge: A Survey

Resource-constrained IoT devices, such as sensors and actuators, have become ubiquitous in recent years. This has led to the generation of large quantities of data in real-time, which is an appealing target for AI systems. However, deploying machine learning models on such end-devices is nearly impossible. A typical solution involves offloading data to external computing systems (such as cloud servers) for further processing but this worsens latency, leads to increased communication costs, and adds to privacy concerns. To address this issue, efforts have been made to place additional computing devices at the edge of the network, i.e., close to the IoT devices where the data is generated. Deploying machine learning systems on such edge computing devices alleviates the above issues by allowing computations to be performed close to the data sources. This survey describes major research efforts where machine learning systems have been deployed at the edge of computer networks, focusing on the operational aspects including compression techniques, tools, frameworks, and hardware used in successful applications of intelligent edge systems.

Grid-Forming Control Suitable for Large Power Transmission System Applications

The inner cascaded structure-based grid-forming control is a typical solution used to impose an AC voltage magnitude across the output filters of the power inverters. Yet, because of the limited inverter’s bandwidth resulting from the low-switching frequencies in transmission systems, the interaction (i.e., coupling) between control loops is highly likely making the understanding of the system behavior complex and its simplification unaffordable and may also lead to instabilities. The novelty of this paper consists in proposing a simple open-loop direct voltage control to reduce the number of the inner control regulators, and thereby guaranteeing a decoupling between the inner and outer control layers as well as increasing the system stability margin. This statement is well supported with a small-signal analysis and progressive order model reduction of the system. The overall concept is validated in a 10-bus grid case while comparing the EMT and Phasor-based simulations. The practical feasibility of the control itself is experimentally proved with different test cases.

Grid-Forming Control Suitable for Large Power Transmission System Applications

The inner cascaded structure-based grid-forming control is a typical solution used to impose an AC voltage magnitude across the output filters of the power inverters. Yet, because of the limited inverter’s bandwidth resulting from the low-switching frequencies in transmission systems, the interaction (i.e., coupling) between control loops is highly likely making the understanding of the system behavior complex and its simplification unaffordable and may also lead to instabilities. The novelty of this paper consists in proposing a simple open-loop direct voltage control to reduce the number of the inner control regulators, and thereby guaranteeing a decoupling between the inner and outer control layers as well as increasing the system stability margin. This statement is well supported with a small-signal analysis and progressive order model reduction of the system. The overall concept is validated in a 10-bus grid case while comparing the EMT and Phasor-based simulations. The practical feasibility of the control itself is experimentally proved with different test cases.

Extended galleries above the porch in two mosques: Qualitative analysis of mosques with wooden minaret in Bosnia and Herzegovina

Among the many mosques from the Ottoman period in Bosnia and Herzegovina, the most numerous are modest and predominantly wooden mosques covered by a hip roof with an integrated wooden minaret. Although they originate in the long tradition of Turkish single-space mosques, their appearance and construction represent the expression of Bosnian autochthonous architecture. They were mostly built for the needs of the neighborhood (mahala) in smaller and larger towns, but also in rural areas. Due to the perishable materials and various other reasons, they had been renovated several times so changes in appearance were in some cases quite certain. These structures have been insufficiently researched and very few valuable publications are available so far. Qualitative analysis of significant examples, in addition to the common features by which these mosques differ from large monumental mosques, differences in the spatial concept, as well as the construction of individual elements, were observed. Concerning the shape of the entrance, these mosques have four characteristic solutions: a mosque with a porch, with a porch and a gallery, without a porch, and with a closed vestibule. The analysis also showed that the two mahala mosques in Tuzla had a specific gallery form that deviated from the typical solution. These galleries are extended over the porch on three sides by the application of ingenious carpentry solutions and covered with elongated eaves. In addition, this study showed that thanks to available sources, it was possible to re-establish the original form of the two mosques, which had since been altered.

Least-thickness symmetric circular masonry arch of maximum horizontal thrust

This analytical note shall provide a contribution to the understanding of general principles in the Mechanics of (symmetric circular) masonry arches. Within a mainstream of previous research work by the authors (and competent framing in the dedicated literature), devoted to investigate the classical structural optimization problem leading to the least-thickness condition under self-weight (“Couplet-Heyman problem”), and the relevant characteristics of the purely rotational five-hinge collapse mode, new and complementary information is here analytically derived. Peculiar extremal conditions are explicitly inspected, as those leading to the maximum intrinsic non-dimensional horizontal thrust and to the foremost wide angular inner-hinge position from the crown, both occurring for specific instances of over-complete (horseshoe) arches. The whole is obtained, and confronted, for three typical solution cases, i.e., Heyman, “CCR” and Milankovitch instances, all together, by full closed-form explicit representations, and elucidated by relevant illustrations.

Perovskite Solar Cells with PCE over 19% Fabricated under Air Environment by Using Dye Molecule Additive

The typical solution-processed perovskite film possesses numerous defects, especially fabricated under high-humidity ambient conditions, which severely limits the performance of planar perovskite solar cells (PSCs). Here, the unique fluorescent dye...

Blockchain Innovation and Information Technology at GCC

Blockchain has become an epidemic and significant decision that organizations may make in the next few years, enabling institutions to integrate business functions, operations, and processes in a decentralized distributed ledger technology. This technology will transform the business world and economy in solving the limitations created by centralization and system inefficiency. Accordingly, with the high demand and complexity of growing economies such as the Gulf Cooperation Council GCC countries, the need for a typical solution technology is a game changer. This will lead GCC to a solid economic base. Blockchain technology can be applicable in many different fields such as Banking, education, Health, finance, government and trade. This article will address the literature review and methodology of Blockchain technology and innovation at the GCC, particularly in Saudi Arabia. Also, more research can be conducted in the future as the system may be integrated in these countries.

The Framework for Blockchain Innovation and the Impact on Digital Economic Transformation

Blockchain technology has become an epidemic and significant decision that organizations may make in the next few years, as integrated business solution enabling institutions to integrate business functions, operations, and processes in a decentralized distributed ledger technology. This technology will transform the business world and economy in solving the limitations created by centralization and system inefficiency. Accordingly, with the highly demanding and complexity of growing economies such as Gulf Cooperation Council GCC countries, the need for a typical solution technology is a game changer. The result of this will lead GCC to a solid base of the economy. Blockchain technology can be applicable in many different fields such as: banking, education, health care, finance, government, trade, etc. This article will propose a conceptual framework for the acceptance of Blockchain technology and innovation in the GCC, particularly in Saudi Arabia. Also, more research can be conducted in the future as the system might be integrated in these countries.

Assessment of downward draught in high-glazing facades in cold climates – experimental and CFD study into draught control with a 21-type radiator

This paper investigates the interaction of a radiator’s thermal plume and downdraught of cold glazed surfaces. Draughts in working areas are one of the most common thermal comfort complaints in modern buildings. A typical solution for dealing with these draughts is positioning the heat emitters such as radiators or convectors under the windows. However, with thermally efficient envelopes, the internal loads compromise a relatively high fraction of the heating demand and the emitters are working under partial loads in modern buildings. This study comprises two parts: an experimental phase in the EN442 standardized test chamber with a 21-type radiator, and a CFD simulation phase, where the model is validated and applied under an expanded set of boundary conditions. The expanded simulation set results provide preliminary insight into sizing and design. More specifically, the thermal plume can be parametrised with a velocity and temperature value along with the room air and glazing temperatures for a broader analysis and assessment of the risk of draught.

Harvesting geothermal energy with low unit cost installations

In the Netherlands, most geothermal energy is utilized for commercial greenhouse heating and is harvested from aquifers located at depths between 2 and 3 km. Typically, the design consists of two wells: a slanted production well and a slanted injection well that are spaced approximately 1.5 km apart in the aquifer formation. Subsidized exploitation is feasible if high volumes can be produced over long periods of time. This typical solution restricts the use of geothermal energy to high-demand applications in areas with suitable high-quality aquifers. We argue that harvesting geothermal energy is economically feasible almost anywhere in the Netherlands with an alternative concept of low unit cost (LUC) installations. LUC produces at a limited rate from cleverly designed high-quality installations that can be developed at a considerably lower cost. We discuss the LUC concept and its economics based on a project for commercial greenhouse heating in the eastern part of the Netherlands. We carry out a reinterpretation of publicly available 3D seismic and offset well data. The Early Cretaceous Bentheim Sandstone was identified as a suitable aquifer for LUC development. At the proposed well location, the top Bentheim is located at a depth of approximately 1500 m, corresponding to about 61°C. We predict a reservoir thickness of approximately 54 m, with a porosity of up to 25% and sufficient permeability. The LUC concept begins by drilling a pilot hole for static and dynamic aquifer characterization. Based on these test results, we decide on the final architecture and placement of wells. Our calculations show that a 1.5 megawatt thermal (MWth) geothermal plant is economically viable, even without government subsidy.