Design of a tensegrity servo-actuated structure for civil applications

The use of glass elements in civil engineering is spreading in the last years beyond merely aesthetic functions for their ease of installation and production. Nonetheless, the structural performance of such materials in any condition of use is object of investigation. In this scenario, the paper analyses the performance of an innovative concept of tensegrity floor (Patent no 0001426973) characterized by a particular steel-glass adhesive junction that permits a profitable structural cooperation between such basically different materials. As known, at the base of the effectiveness of tensegrity structures lies the correct tensioning of metal strands which are devoted at keeping the rigid elements compressed. The tensioning level is then responsible of the actual deformation of the structure, which is of course of uttermost importance while speaking of civil applications. To address this issue with the adequate level of confidence required by construction practice, a mechatronic servo-system is proposed, aimed at maintaining, and modifying when needed, the stress state of the metal cables to adjust the deformation of the upper plane in response to varying loads. Three different actuation schemes, with different levels of realization complexity, are analysed and compared in simulated environment by means of a hybrid multibody-finite elements model.

Multibody Analysis of a Tensegral Servo-Actuated Structure for Civil Applications

The use of glass elements in civil engineering is spreading in the last years beyond merely aesthetic functions for their ease of installation and production. Nonetheless, the structural performance of such materials in any condition of use is object of investigation. In this scenario, the paper analyses the performance of an innovative concept of tensegrity floor (Patent no 0001426973) characterized by a particular steel-glass adhesive junction that permits a profitable structural cooperation between such basically different materials. As known, at the base of the effectiveness of tensegral structures lies the correct tensioning of metal strands which are devoted at keeping the rigid elements compressed. The tensioning level is then responsible of the actual deformation of the structure, which is of course of uttermost importance while speaking of civil applications. To address this issue with the adequate level of confidence required by construction practice, a mechatronic servo-system is proposed, aimed at maintaining, and modifying when needed, the stress state of the metal cables to adjust the deformation of the upper plane in response to varying loads. Three different actuation schemes, with different levels of realization complexity, are analysed and compared in simulated environment by means of a hybrid multibody-finished elements mode.

Evaluation of Techniques to Describe Device Complexity in Pre and Post Design Stages

Electro-Mechanical device complexity exists in everyday items from cell phones to automobiles to vacuum cleaners. Generally, product complexity is one of the least quantifiable characteristics in the design cycle with arguably some of the greatest implications. A high level of device complexity carries a negative connotation and is usually considered an attribute a designer should attempt to mitigate. Alternatively, a low level of device complexity may induce designers and marketers to question a product’s usefulness. Whether complexity is a necessary aspect of a design or a hindrance needing to be minimized or eliminated, depends upon how complexity is framed. Some instances in literature attempt to measure complexity yet there is no unified measure that captures the complexity of a product or system during design phases or upon product/system realization. Complexity is defined in many ways, at different levels of abstraction, and different stages of design therefore, becoming highly contextual and subjective at best. An established and repeatable methodology for calculating complexity of existing products in the marketplace is necessary. Once a measure of complexity is agreed upon at the post design stage we can look to earlier phases in design to see whether insights are observable. Identifying complexity early in the design cycle is paramount to strategic resource allocation. This study considers the Generalized Complexity Index (GCI) measure put forth by Jacobs [1] and expands upon it to include functional modeling as a key component in determining an indicative complexity metric. Functional modeling is a method used to abstract system or product specifications to a general framework that represents a function based design solution. Complexity metrics are developed at the functional and completed design levels and used for comparison. Thirty common household products retrieved from an online design repository [2] as well as seven senior capstone design projects were evaluated using the GCI. A modification to the GCI equation is proposed and to gain a relative scale of complexity within the data, a ranked complexity metric was developed and utilized. The magnitude of the ranked complexity metric was only indicative of hierarchical status of a product within the data set and therefore is not comparable to GCI values. Though Jacobs GCI worked well in his study, the GCI does not represent a meaningful complexity measure when applied to the data in this study. This study is an initial attempt to apply an independent data set to Jacobs GCI model with perhaps greater implications, with respect to products, that complexity is multifaceted and is not accurately represented by only interconnectedness, multiplicity, and diversity.

A Fast Acquisition Scheme for Coherent DDS/FFH System

For a coherent DDS/FFH system (deeply direct sequence and coherent fast frequency hopping hybrid spread spectrum system), signal has a very large spread spectrum ratio. Signal acquisition process becomes very complex and difficult due to interference and doppler frequency shift in a strong interfering and high dynamical environment. FFT corelation sequence points are very large if traditional frequency-based FFT acquisition scheme is used, FFH requires FFT operation should be completed in a much shorter time (within one hopping duration time), which makes system realization become very complex or even impossible. A partial matched filter combining FFT, coherent accumulation combining incoherent accumulation acquisition scheme is investigated, system realization complexity is reduced.

MULTI ATTRIBUTE DECISION MAKING: ASSESSING THE TECHNOLOGICAL AND OPERATIONAL PARAMETERS OF AN AIRCRAFT

Regional aircraft are playing a significant role in airline operations. This paper considers the problem of selecting an appropriate aircraft from the airline fleet for optimal regional air travel realization. Complexity balance between air travel demand (passengers, goods) and the proposed aircraft capacity presents the priority in airline operations. A principal feature of the methodology considered in this paper is a multi attribute analysis of technological and operational aircraft characteristics (turboprop and turbojet). A comparison of the presented regional aircraft parameters is based on the following criteria: technological (aerodynamic efficiency, structural efficiency, fuel flow at the optional FL, cruise endurance and requested trip fuel for the fixed cruise range), operational (max range with max payload, ground efficiency (aircraft maintainability based on external dimensions) and climb capability. With the aim of defining aircraft rank, the TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) method was applied. Therefore, the Saaty scale was used for developing the weight of different criteria. The conducted research included a sample of four representative regional aircraft: Do328, CRJ100er, Saab2000 and ERJ145. The results obtained would help in determining the airline fleet or selecting the optional solution from the existing fleet.