Single-step alkaline etching of deep silicon cavities for chip-scale atomic clock technology

This paper presents the results of experiments on the development of the technology of MEMS alkali vapor cells for a miniature quantum frequency standard. The classical design of a two-chamber silicon cell containing an optical chamber, shallow filtration channels and a technical container for a solid-state alkali source was implemented in a single-step process of wet anisotropic silicon etching. To prevent the destruction of the filtration channels during etching of the through silicon cavities, the shapes of the compensating structures at the convex corners of the silicon nitride mask were calculated and the composition of the silicon etchant was experimentally found. The experiments results were used in the manufacture of chip-scale atomic clock cells containing vapors of 87Rb or 133Cs isotopes in the neon atmosphere.

Design and Modeling of an Experimental ROV with Six Degrees of Freedom

With the development of underwater technology, it is important to develop a wide range of autonomous and remotely operated underwater vehicles for various tasks. Depending on the problem that needs to be solved, vehicles will have different designs and dimensions, while the issues surrounding reduced costs and increasing the functionality of vehicles are relevant. This article discusses the development of inspection class experimental remotely operated vehicles (ROVs) for performing coastal underwater inspection operations, with a smaller number of thrusters, but having the same functional capabilities in terms of controllability (as vehicles with traditionally-shaped layouts). The proposed design provides controllability of the vehicle in six degrees of freedom, using six thrusters. In classical design vehicles, such controllability is usually achieved using eight thrusters. The proposed design of the ROV is described; the mathematical model, the results of modeling, and experimental tests of the developed ROVs are shown.

A Bio-Inspired Method for Engineering Design Optimization Inspired by Dingoes Hunting Strategies

A novel bio-inspired algorithm, namely, Dingo Optimization Algorithm (DOA), is proposed for solving optimization problems. The DOA mimics the social behavior of the Australian dingo dog. The algorithm is inspired by the hunting strategies of dingoes which are attacking by persecution, grouping tactics, and scavenging behavior. In order to increment the overall efficiency and performance of this method, three search strategies associated with four rules were formulated in the DOA. These strategies and rules provide a fine balance between intensification (exploitation) and diversification (exploration) over the search space. The proposed method is verified using several benchmark problems commonly used in the optimization field, classical design engineering problems, and optimal tuning of a Proportional-Integral-Derivative (PID) controller are also presented. Furthermore, the DOA’s performance is tested against five popular evolutionary algorithms. The results have shown that the DOA is highly competitive with other metaheuristics, beating them at the majority of the test functions.

The not so universal hero’s journey

Since the 1990s, Joseph Campbell’s research into mythology has become a cornerstone of the most influential and deeply entrenched model of screenwriting practised and taught internationally. Campbell’s finding that the quest myth, the hero’s journey, is ubiquitous around the globe, across human time, and therefore universal is constantly cited to prove the universality of what Robert McKee calls ‘classical design’; the story of a protagonist facing obstacles in pursuit of a goal. However, a close analysis of three of the myths and rituals, which Campbell cites to prove his theory, demonstrate he misinterpreted the meaning of the myths. Knowingly or not, he projected Anglo-Western storytelling and cultural values onto Indigenous mythic narratives, which in fact have very different storytelling norms and serve a very different purpose to the individualistic striving for self-fulfilment which he identified. Given this, it is time for practitioners and teachers to stop claiming that the hero’s journey and by default classical design are universal. Given the current struggle for inclusion of diverse, multi-cultural and marginalized voices into mainstream storytelling, this corrective is well overdue.

Pseudococyclic Partial Hadamard Matrices over Latin Rectangles

The classical design of cocyclic Hadamard matrices has recently been generalized by means of both the notions of the cocycle of Hadamard matrices over Latin rectangles and the pseudococycle of Hadamard matrices over quasigroups. This paper delves into this topic by introducing the concept of the pseudococycle of a partial Hadamard matrix over a Latin rectangle, whose fundamentals are comprehensively studied and illustrated.

Steps of generative design in integrated CAD systems

Due to the continuous development of various areas of the industry, such as modern production equipment, material technology, computer and software development, it is possible to expand the range of conventional production technologies. These include additive manufacturing technology, which provides a new opportunity to produce everyday products, thereby satisfying market needs. Integrated CAD systems have occupied a place in the product design and development process for decades, which has partially reformed classical design methods and its steps.

Simulation and improvement of the separation process of synthesizing vinyl acetate by acetylene gas-phase method

Vinyl acetate, as an essential organic chemical raw material, can be used to produce polyvinyl acetate, polyester vinyl alcohol, and other products. The existing classical vinyl acetate production process has the problems of low product purity and excessive heat load. In this study, in the classical design of the process, acetylene is separated first, and then acetaldehyde is removed with the formation of an azeotrope between ethylene acetate and water. Meanwhile, considering the solubility of acetaldehyde in water and insolubility of vinyl acetate in water, the process was optimized to separate acetic acid after removing acetylene, so as to avoid the azeotrope formation of vinyl acetate and water. The nonrandom two-liquid-Hayden–O’Connell thermodynamic hybrid model was used to simulate the classical process and improved process (IP). Finally, the reflux ratio and theoretical tray number of the main separation equipment of IP were optimized to get the better parameters. The simulated results show that the purity of vinyl acetate increased from 99.1% to 99.8%, the cooling energy consumption was reduced by 16.83%, and the thermal energy consumption was reduced by 6.18%. At the same time, the equipment investment was also decreased.

Improvement of the performance of a capacitive relative pressure sensor: case of large deflections

Capacitive pressure sensors are widely used in a variety of applications and are built using a variety of processes, including 3D printing technology. The use of this technology could lead us to a situation of large deflections, depending on the mechanical properties of the materials and the resolution of the machines used. This aspect is rarely reported in previous research works that focus on improving the performance in terms of linearity and sensitivity of these sensors. This paper describes the realization of relative pressure sensors designed as two different structures; the first one is the classical design composed of a single capacitor, while the second one is composed of two capacitors, designed in such a way that they both vary according to the applied pressure but in opposite senses to each other. The purpose is to study in particular the performance of the second structure in the case of large deflections for the context of educational use. Polylactic acid (PLA) is used as the manufacturing material to print the sensors by means of a printer based on fused deposing modeling, while conductive materials are used to provide the electrical conductivity required for the printed sensors. The manufactured sensors were tested under pressure in the range of [0; 9] KPa. Compared to the performance obtained with the first structure, simulation and experimental results show that the second structure improves linearity and allows the sensitivity to be increased from a minimum of 9.98×10-2 pF/hPa to a minimum of 3.4×10-1 pF/hPa.

‘Un'arte ancora in embrione’: international expositions, empire, and the evolution of Fascist architectural design

This article reconsiders the development of Fascist architecture throughout the late interwar period. It pays especial attention to the structures erected for the most significant international expositions held, or planned to be held, between 1933 and 1942, in order to identify significant trends in Party-sponsored design. It argues that the ‘dynamism’ of Fascist design was a consequence of the regime's preference for an increasingly imperial tone which developed in direct proportion to its increasingly imperial identity. It points to Piacentini and Pagano's Italian Pavilion built for the 1937 Paris Exposition, the first national pavilion constructed following the May 1936 proclamation of empire, as a significant flashpoint in the tension between Fascist interpretations of modern and classical design. This article concludes that the often-overlooked world's fair buildings can be viewed as crystalline distillations of the stylistic experimentation which defined the broader Fascist building programme both in Italy and abroad.