Flutter analysis of piezoelectric beams in MEMS

Micro-electro-mechanical systems (MEMS) represent a huge class of devices characterized by the smart coupling between electronics and mechanics, in order to obtain microscopic sensors and actuators. The use of piezoelectric materials in MEMS is steadily increasing, considering both the “direct effect”, e.g. in energy harvesters, and the “indirect effect”, for the cases of resonators, micropumps and other actuators. This paper is devoted to the study of piezoelectric laminate beams in the presence of aeroelastic effects due to the interaction of the structure with a fluid flow, as it may happen if the MEMS is embedded in a fluidic system. More specifically, the analytical conditions for the onset of flutter instability are studied, with the purpose of providing a sound basis for further studies focused on energy harvesting from fluid flows

Stability of dynamic response of suspension bridges

The potential occurrence of internal parametric resonance phenomena has been recently indicated as a potential contributory cause of the appearance of critical dynamic states in long-span suspension bridges. At the same time, suspension bridges, in view of their flexibility, are prone to aeroelastic response, such as vortex shedding, torsional divergence and flutter. In this paper, a non-linear dynamic model of a suspension bridge is devised, with the purpose of providing a first attempt toward a unified framework for the study of aeroelastic and internal resonance instabilities. Inspired by the pioneering work of Herrmann and Hauger, the analyses have been based on a linearized formulation that is able to represent the main structural non-linear effects and the coupling given by aerodynamic forces. The results confirm that the interaction between aeroelastic effects and non-linear internal resonance leads to unstable conditions for wind speeds which can be lower than the critical threshold for standard aeroelastic predictions

Improved one-dimensional model of piezoelectric laminates for energy harvesters including three dimensional effects

The application of piezoelectric composites in energy harvesters is continuously increasing even at the microscale, with the immediate corollary of a fundamental need for improved computational tools for optimization of performances at the design level. In this paper, a refined, yet simple model is proposed with the aim of providing fast and insightful solutions to the multi-physics problem of energy harvesting via piezoelectric layered structures. The main objective is to retain a simple structural model (Euler–Bernoulli beam), with the inclusion of effects connected to the actual three-dimensional shape of the device. A thorough presentation of the analytical model is presented, along with its validation by comparison with the results of fully 3D computations

Electrostatic diaphragm micropump electro-fluid-mechanical simulation

In this work, a fully-silicon mechanical displacement micropump is proposed and investigated. Electrostatic actuation of a flexible diaphragm is used to generate the pressure difference required to transport the fluid at the microscale. The study is carried out by exploiting the Finite Element method in a multiphysics framework, considering simplified geometries and boundary conditions. These investigations suggest the possibility to adopt the proposed device for applications in biomedical and biological fields. Achievable stroke volumes and flow rates are computed: values are in line with those obtained for similar devices presented in the literature

Shape optimization of solid-air porous phononic crystal slabs with widest full 3D bandgap for in-plane acoustic waves

The use of Phononic Crystals (PnCs) as smart materials in structures and microstructures is growing due to their tunable dynamical properties and to the wide range of possible applications. PnCs are periodic structures that exhibit elastic wave scattering for a certain band of frequencies (called bandgap), depending on the geometric and material properties of the fundamental unit cell of the crystal. PnCs slabs can be represented by plane-extruded structures composed of a single material with periodic perforations. Such a configuration is very interesting, especially in Micro Electro-Mechanical Systems industry, due to the easy fabrication procedure. A lot of topologies can be found in the literature for PnCs with square-symmetric unit cell that exhibit complete 2D bandgaps; however, due to the application demand, it is desirable to find the best topologies in order to guarantee full bandgaps referred to in-plane wave propagation in the complete 3D structure. In this work, by means of a novel and fast implementation of the Bidirectional Evolutionary Structural Optimization technique, shape optimization is conducted on the hole shape obtaining several topologies, also with non-square-symmetric unit cell, endowed with complete 3D full bandgaps for in-plane waves. Model order reduction technique is adopted to reduce the computational time in the wave dispersion analysis. The 3D features of the PnC unit cell endowed with the widest full bandgap are then completely analyzed, paying attention to engineering design issues

BESO approach to topology optimization of GaN phononic crystals

The use of Phononic Crystals (PnC) in suspended structures and microstructures, such as plates and slabs, has gained a lot of attention in the past years for the wide range of feasible applications (acoustic waveguides, acoustic insulation, acoustic cloaking) and for the easy fabrication technique. Since the performance of the device is related to the band of frequencies reflected by the PnC and since this band (called bandgap) depends on the geometric and material properties of the fundamental unit cell of the PnC, a useful tool for the design of those structures is topology optimization. This paper is focused on a novel and fast engineering use of Bidirectional Evolutionary Structural Optimization for the definition of the optimal hole configuration in air-solid PnC. The technique adopted finds the optimal shape of the hole in less than 20 iterations, and it is easy implemented in a 2D plane strain Matlab finite element solver

Controllo sistemico e risposta encefalica con lapatinib più capecitabina in II linea di terapia nel carcinoma mammario HER2-positivo, metastatico

Overexpression of the human epidermal growth factor receptor (HER2) oncoprotein in breast cancer patients, is one of the biological characteristics of the disease that determines the choice of appropriate systemic treatment. We report the case of a 41-year-old woman, with relapsing HER2-positive breast cancer in cerebral and pulmonary cells. The patient underwent multimodal first Iine treatment including pertuzumab, trastuzumab and docetaxel and panencephalic radiotherapy with good response and progression-free survival for approximately 16 months. Subsequently, further to a encephalic progression of the disease, the patient was treated in second line with the combination lapatinib + capecitabine which induced further encephalic response and disease control for additional 20 months (Oncology)

PERANCANGAN GEDUNG PERTUNJUKAN SENI DI BANDA ACEH

ABSTRAKPERANCANGAN GEDUNG PERTUNJUKAN SENIDI BANDA ACEHOleh:Deddy Handayani1004104010047Gedung Pertunjukan Seni di Banda Aceh merupakan suatu wadah bagi para seniman untuk menampilkan karyanya baik berupa seni musik dan tari sehingga dapat ditonton oleh penikmat seni atau masyarakat luas sebagai sarana hiburan dan rekreasi. Lokasi perencanaan terletak di kawasan Jalan Sultan Iskandar Muda, Ulee Lheue Kecamatan Meuraxa yang merupakan kawasan pengembangan rekreasi kota Banda Aceh.Tujuan utama perancangan Gedung Pertunjukan Seni ini diawali dengan pendekatan studi literatur dan studi banding kemudian dilanjutkan dengan tahap identifikasi masalah yang muncul dalam proses perancangan dan melakukan analisa-analisa untuk memberikan tanggapan desain yang sesuai dengan kondisi lingkungan dan fisik bangunan.Hasil pembahasan analisa dituangkan dalam bentuk konsep perancangan gedung dengan tema Arsitektur Neo Vernakuler yang selanjutnya menjadi acuan dalam perancangan bangunan.Kata kunci : Gedung Pertunjukan Seni di Banda Aceh, Arsitektur Neo VernakularABSTRACTPERFORMING ARTS BUILDING DESIGNIN BANDA ACEHBy:Deddy Handayani1004104010047Performing Arts Building in Banda Aceh is a facility for artists to perform their works like musics and dance, soit can be watched by public as entertainment and also recreation. Site plan of this design located in Jalan Sultan Iskandar Muda District, Ulee Lheue Kecamatan Meuraxa where is an area of recreational development of Banda Aceh City.The main purpose of this Performing Arts Building Design is started by aproaching literatue and comparative studies and then the step is followed by the identification problems in design proses and after that conduct analyzes to provide an apropriate response to the environmental and physical conditions of the building.The results of this discussion is made in set forth in the form of building design concept with the Architecture Neo Vernacular concept which became a reference in building designing.Keywords : Performing Arts Building in Banda Aceh, Architecture Neo VernacularBanda Ace