Optimal sensor placement for joint parameter and state estimation problems in large-scale dynamical systems with applications to thermo-mechanics

We consider large-scale dynamical systems in which both the initial state and some parameters are unknown. These unknown quantities must be estimated from partial state observations over a time window. A data assimilation framework is applied for this purpose. Specifically, we focus on large-scale linear systems with multiplicative parameter-state coupling as they arise in the discretization of parametric linear time-dependent partial differential equations. Another feature of our work is the presence of a quantity of interest different from the unknown parameters, which is to be estimated based on the available data. In this setting, we employ a simplicial decomposition algorithm for an optimal sensor placement and set forth formulae for the efficient evaluation of all required quantities. As a guiding example, we consider a thermo-mechanical PDE system with the temperature constituting the system state and the induced displacement at a certain reference point as the quantity of interest.     

A comparison study of Taiwanese He-Yuan Architecture between the ethically spatial order and the condition of physical environment

Since the 21st century, problems such as global warming and energy depletion have become important issues to scientists and architects. The architectural design nowadays often relies on large amount of mechanical equipment to create a comfortable environment for the users. However, it burdens and deteriorates the nature. On the other hand, some of the traditional architecture in the past can cope with the local humid and hot climate, achieving good passive heat control for the environment. Therefore, this study explores the relation between traditional residents in Taiwan’s use of space and the external environment and climate through modern environment measurement technique, restores and conducts quantitative analysis on the interior thermal environment and light environment of Lin-An-Tai Historical House in the past through Ecotect Analysis, and analyzes the results of the calculation in terms of its spatial allocation, openings, and outer walls, etc. This study also evaluates the effects of lighting and user’s sense of comfortable temperature under its environmental conditions according to the standards of residential quality nowadays. It further studies the ancestor of traditional architecture by reviewing its spatial order and compares to the current situation in order to feedback the modern architecture design. Part of the results of the simulation show that the variation of temperature indoors in each space is less dynamic than that of outdoors. The temperature in the space at the right of the main hall (northwestern side) is generally higher than that in the left (southeastern side). The highest temperature in the space farther away from the interior patio is usually higher than that in the space closer to the interior patio. The temperature near the outer side of the space above Hulong is higher than that in the middle. Accordingly, the location is closely related to the interior temperature. As to human’s sense of comfortable temperature, the results show that in summer, the Predicted Mean Vote (PMV) in the space at the left of the main hall (southeastern side) is generally higher than that in the right (northwestern side). In winter, the sense of comfortable temperature in the rooms in the corner is lower than that in other rooms at the inner side, the comparison between the space ethical order and the evaluation result did not show any obvious relationship. For the evaluation of lighting, the main hall and the restaurant at the outer left Hulong have better lighting while other space does not have sufficient and even lighting. Artificial lighting is needed to make the space more functional, the results shows that lighting conditions of space did not metaphor to the space ethical order.     

An experimental investigation on slope stability under drawdown conditions using transparent soils

This paper presents an experimental investigation into slope failure during water-level drawdown using transparent soil. The internal characteristics of slope failure are not well-known due to the limitations of the techniques used in the experiments conducted to date. In this study, transparent soil is used to visualize the process of slope failure. We developed a water-level control system to implement simulation of the drawdown of the water level at various speeds and used a charge-coupled device camera to capture images during the entire slope failure process. Particle image velocimetry was used to measure the displacement of the sand particles and identify the sliding zones. The flow paths of the fluid inside the slope were illuminated using an organic dye. The results show that the slope failure process can be divided into two stages: surface and overall sliding. The overall sliding of the slope is caused by the gradual development of partial instability, and the failure mode is a cyclic failure. The slope angle is different above and below the water level during the process of sliding. In our experiments, the slope angle is about 20° above the water level, which is the same as the final stable slope angle, and about 35° below the water level, which is the same as the initial slope angle. This means that the drawdown influences the angle above the water level but has little influence on the angle below the water level. The results of this paper provide a better understanding of the physical behavior and failure mode of soil slopes caused by drawdowns near the coast.     

A Novel Approach for Bolted T-Stub Connections

This paper reports an investigation into new connection types and their behaviors determined using full-scale experiments. T-shaped connections were created using the IPE standard profile. The aim of this study was to analyze the influence of T connections based on the IPE standard profile, height of beam to height of T-stub joint (H) of T-stub joints, and lengths (X) of T-stub joints on the behavior of steel connections, in order to provide the necessary data for improving Eurocode 3 and enable efficient use of residue IPE standard profiles and back to the consumption cycle. While the moment resistance values increased with an increase in H from H_min to H_max in model groups with X of 126 mm, and the energy dissipation increased with an increase in H from H_min to H_max and also with an increase in the lengths (X) of T-stub joints from 54 to 126 mm.     

Numerical implementation of drop and tilt method of five-axis tool positioning for tensor product surfaces

The Drop and Tilt tool position method for five-axis machining positions a toroidal tool to have two points of contact with a tensor product Bézier surface. The method results in high order simultaneous non-linear transcendental equations that are slow to solve. In this paper, an efficient numerical implementation of the Drop and Tilt Method of multi-point tool positioning on tensor product surfaces is presented. The method was implemented in C++, and is a direct method that does not convert the tensor product surface into an intermediate representation such as triangles or point clouds. The method is successfully demonstrated on a number of tensor product Bézier surfaces.     

Electron beam processed surface textures on titanium alloys for fluid-drag reduction

Ti-6Al-4V and Ti-4Al-1.5Mn alloys were employed for electron beam processing with the aim to produce surface textures efficient for fluid-drag reduction. The as-resulted surface textures were examined by using advanced optical microscopy for surface morphology analysis, optical microscopy and scanning electron microscopy for near-surface microstructure observation. The titanium model with electron beam processed surface textures was tested in wind tunnel to evaluate their fluid-drag reduction efficiency. It showed that the as-resulted non-smooth surface was characterized by parallel ridges and grooves, with height and spacing able to be customized by adjusting processing parametres. The ridges displayed continuous scales while the valley of grooves presented V-shaped ripples. Their dimensions were also related to and could be controlled by processing parametres. Further, the near-surface region was occupied by fusion zone, heat-affected zone and base metal from the outermost surface to the underlying bulk alloy. The microstructure of fusion zone was characterized by martensite phase. A heat-affected zone was sandwiched between fusion zone and the underlying base metal, with different microstructural features compared to both fusion zone and the base metal. With respect to fluid-drag reduction efficiency, titanium model with electron beam processed surface textures exhibits a reducing efficiency over 15% at attack angles of 0° and ±1°, with an air flow velocity at 24 m/s.     

The role of psychology and social influences in energy efficiency adoption

Current energy efficiency policy and incentive programs tend to target economic motivations, which may misalign with other potentially important motivations arising from situational factors, individual differences, and social context. Thus, in this research, we review areas of work that have focused on psychological and social influences to energy efficiency adoption in commercial buildings. We then conduct an empirical scoping study interviewing 10 commercial building owners/managers (decision makers) and 10 experts/consultants (decision influencers) regarding perceived motives and barriers to energy efficient investments, decision-maker attributes, and the social context of the decision. Potential factors that emerge from the interviews, which are not yet extensively discussed in the energy efficiency literature, include owners/managers’ resistance to change and the influence of investment funding origins on the decision. Our results also suggest potential heterogeneity in energy efficiency decision-making philosophies between the two groups. Interviewed owners/managers prioritize corporate social responsibility (CSR) and prefer internal consulting (e.g., building engineers). Conversely, experts/consultants do not emphasize CSR and are more concerned with external policies. These findings suggest that accounting for the decision maker and the social context in which decisions are made could enhance the design of commercial sector energy efficiency programs.     

Climate dependence of energy saving strategies in public buildings characterized by change of use: an original case study

In the perspective of reducing land occupation of built environments, the most efficient strategy is to increase the reuse of obsolete or abandoned constructions instead of designing new buildings. This is particularly true regarding public buildings, usually characterized by considerable dimensions. The paper is focused on this issue, particularly on its energy implications. It analyzes the headquarters of the “G. D’Annunzio” University in Pescara, Italy, initially designed for commercial use and later converted to a university building during its construction. The authors first carried out a numerical analysis of the building energy performance in its current state and then they proposed some improvement interventions evaluating their incidence on the annual energy balance of the building, showing how the most commonly used energy saving strategies do not give the best results in any case, being greatly influenced by the climatic zone in which the building is located. Starting from these considerations, the authors carried out the analysis by considering three different Italian climatic conditions so as to determine their influence on the building energy performance and to define the best strategy for energy requalification in each climatic zone.     

Evaluation on Dorsey Method in Surface Tension Measurement of Solder Liquids Containing Surfactants

With the purpose of developing a feasible approach for measuring the surface tension of solders containing surfactants, the surface tension of Sn–3Ag–0.5Cu–xP solder alloys, with various drop sizes as well as different phosphorus (P) content, was evaluated using the Dorsey method based on the sessile drop test. The results show that the accuracy of the surface tension calculations depends on both of sessile drop size and the liquid metal composition. With a proper drop size, in the range of 4.5 mm to 5.3 mm in equivalent spherical diameters, the deviation of the surface tension calculation can be limited to 1.43 mN·m^?1 and 6.30 mN·m^?1 for SnAgCu and SnAgCu–P, respectively. The surface tension of SnAgCu–xP solder alloys decreases quickly to a minimum value when the P content reaches 0.5 wt% and subsequently increases slowly with the P content further increasing. The formation of a P-enriched surface layer and Sn₄P₃ intermetallic phases is regarded to be responsible for the decreasing and subsequent increasing of surface tension, respectively.