Investigation and Computational Modelling of Variable TEG Leg Geometries

In this work, computational modelling and performance assessment of several different types of variable thermoelectric legs have been performed under steady-state conditions and the results reviewed. The study conducted has covered geometries, not previously analysed in the literature, such as Cone-leg and Diamond-leg, based on the corresponding thermoelectric generator leg shape structure. According to the findings, it has been demonstrated that the inclusion of a variable cross-section can have an impact on the efficiency of a thermoelectric generator. It has been concluded that the Diamond configuration generated a slightly larger voltage difference than the conventional Rectangular geometry. In addition, for two cases, Rectangular and Diamond configurations, the voltage generated by a TEG module consisting of 128 pairs of legs was analysed. As thermal stress analysis is an important factor in the selection of TEG leg geometries, it was observed based on simulations that the newly implemented Diamond-leg geometry encountered lower thermal stresses than the traditional Rectangular model, while the Cone-shape may fail structurally before the other TEG models. The proposed methodology, taking into account the results of the simulation carried out, provides guidance for the development of thermoelectric modules with different forms of variable leg geometry.

Influence of Atomization Characteristics on Lean Blow-Out Limits in a Gas Turbine Combustor

In order to investigate the effects of atomization characteristics on the lean blow-out (LBO) performance, an experimental study was carried out on the spray and the combustion. The LBO limits and the outlet temperature near the LBO condition of different atomizers were measured in a single dome rectangular model combustor with a dual-radial and a dual-axial swirl cup, respectively. In the combustor, the spray analysis was performed on different atomizers (without combustion) at the LBO condition. The Malvern particle size analyzer was used to measure the Sauter Mean Diameter (SMD), and the laser sheet was used to take spray images. First of all, the spray pattern determines the minimum heat release required to maintain the combustion, which corresponds to the ideal LBO fuel/air ratio (FAR), which is the maximum potential for the lean combustion. Secondly, the matching of the spray SMD, the droplet size spatial distribution and the droplet initial velocity with the flow field determines the ratio of the completely burned fuel to the total fuel ejected from the atomizer, which determines the extent to which the combustor exerts its lean combustion potential. In addition, the numerical simulation of the flow field of the combustor with two structures was carried out, which provided an important basis for the theoretical analysis of this paper.

Development of Virtual Metrology Using Plasma Information Variables to Predict Si Etch Profile Processed by SF6/O2/Ar Capacitively Coupled Plasma

In the semiconductor etch process, as the critical dimension (CD) decreases and the difficulty of the process control increases, in-situ and real-time etch profile monitoring becomes important. It leads to the development of virtual metrology (VM) technology, one of the measurement and inspection (MI) technology that predicts the etch profile during the process. Recently, VM to predict the etch depth using plasma information (PI) variables and the etch process data based on the statistical regression method had been developed and demonstrated high performance. In this study, VM using PI variables, named PI-VM, was extended to monitor the etch profile and investigated the role of PI variables and features of PI-VM. PI variables are obtained through analysis on optical emission spectrum data. The features in PI-VM are investigated in terms of plasma physics and etch kinetics. The PI-VM is developed to monitor the etch depth, bowing CD, etch depth times bowing CD (rectangular model), and etch area model (non-rectangular model). PI-VM for etch depth and bowing CD showed high prediction accuracy of R-square value (R2) 0.8 or higher. The rectangular and non-rectangular etch area model PI-VM showed prediction accuracy R2 of 0.78 and 0.49, respectively. The first trial of virtual metrology to monitor the etch profile will contribute to the development of the etch profile control technology.

Effects of weir geometry on scour development in the downstream of Piano Key Weirs

Scouring in the downstream of all weirs, including Piano Key Weirs (PKWs), can have major safety implications. Since the research on downstream scouring of PKWs is very limited, and the weir geometry is also known to have an impact on downstream scouring, this study investigated scouring in the downstream of PKWs with rectangular and trapezoidal geometries and two different heights. The scour hole measurements showed that in both rectangular and trapezoidal models, scour hole parameters increased both with the increase in discharge rate and the increase in weir height. Under similar discharge conditions, the scour depth downstream from the rectangular model was greater than that downstream from the trapezoidal model. The dimensionless maximum scour depth, the distance of maximum scour depth from the weir toe, and the scour hole length for the trapezoidal PKW were, on average, 6, 13, and 11% lower than the corresponding ones for the rectangular PKW, respectively. However, these differences decreased with the increase in falling height. For both weir geometries, the maximum scour depth was aligned with the outlet keys. In addition, the maximum scour depth under the outlet keys was 13% greater than the one under the inlet keys.

Comparison of Two Techniques of Pattern Recognition in the Image Analysis-Based Wheat Stalk Length Characterization

The chaff quality or, more specifically, the distribution of stalk length after straw shredding during wheat harvest with a combined harvester is of significant interest for ploughless tillage practices. The currently applied characterization methods (manual length measurement or the cascade sieve analysis) are time-consuming and labour-intensive. Image analysis-based size characterization has the potential to solve these problems. In this study, two techniques of digital image processing, the well-known method of image moments (rectangular model) and a sub-pixel skeletonization approach (flow lines-tracing), were applied comparatively for stalk length measurement. Upon applying the rectangular model, the analyzed stalks were found to be longer than when the flow lines-tracing algorithm was applied. This was attributed to the unbiased decision criteria of the measuring method. A greater length of the stalk is to be expected in the main stalk than when the length of a twisted or branched stalk is measured from the edge length of a rectangular box that encloses it.

Helping Students Acquainted with Multiplication in Rectangular Model

Usually, multiplication is introduced to students to represent quantities that come in group. However there is also rectangular array model which is also related to multiplication. Barmby et al (2009) has shown that the rectangular model such as array representations encourage students to develop their thinking about multiplication as a binary operation with row and column representing two inputs. Considering that finding, this study focusses on a design research that was conducted in Indonesia in which I investigate second grade students’ (between 7 and 8 years old) in Madrasah Ibtidaiyah Negeri (MIN) 2 Palembang, Indonesia, ability to structuring the situation and their ability to represent rectangular model into multiplication sentence. The results shows us that students activity to structuring the situation, looking the number of objects in row or in column, lead them to repeated addition and transform it into multiplication sentence.

The Examination of the Economical Effectiveness of Forest Fire Suppression by Using Theoretical Fire Spread Models

It is commonly known that firefighting is very expensive solution; therefore it isn’t useless to study it by the criteria of efficiency. But the meaning of efficiency for fire managers can be different from the meaning of efficiency for economists. From an economic viewpoint, it is stricter than from a technical view. Method: this research used geometric aspects of the fire spread created rectangular and concentric circles models and used basic mathematic calculations and logical conclusions. Results and discussion: The rectangular model shows the criteria of economic efficiency of firefighting. Moreover, the results from rectangular model can be transferred also to the section of concentric circles model. Based on the concentric circle model we can define both the economic efficiency of fighting forest fire and minimal criteria of successful suppression expressed by the elementary information we have regarding the actual fire.

Adaptive Fault-Tolerant Routing in 2D Mesh with Cracky Rectangular Model

This paper mainly focuses on routing in two-dimensional mesh networks. We propose a novel faulty block model, which is cracky rectangular block, for fault-tolerant adaptive routing. All the faulty nodes and faulty links are surrounded in this type of block, which is a convex structure, in order to avoid routing livelock. Additionally, the model constructs the interior spanning forest for each block in order to keep in touch with the nodes inside of each block. The procedure for block construction is dynamically and totally distributed. The construction algorithm is simple and ease of implementation. And this is a fully adaptive block which will dynamically adjust its scale in accordance with the situation of networks, either the fault emergence or the fault recovery, without shutdown of the system. Based on this model, we also develop a distributed fault-tolerant routing algorithm. Then we give the formal proof for this algorithm to guarantee that messages will always reach their destinations if and only if the destination nodes keep connecting with these mesh networks. So the new model and routing algorithm maximize the availability of the nodes in networks. This is a noticeable overall improvement of fault tolerability of the system.