Roberto Capata

Development of Micro-Grippers for Tissue and Cell Manipulation with Direct Morphological Comparison

Although tissue and cell manipulation nowadays is a common task in biomedical analysis, there are still many different ways to accomplish it, most of which are still not sufficiently general, inexpensive, accurate, efficient or effective. Several problems arise both for in vivo or in vitro analysis, such as the maximum overall size of the device and the gripper jaws (like in minimally-invasive open biopsy) or very limited manipulating capability, degrees of freedom or dexterity (like in tissues or cell-handling operations). This paper presents a new approach to tissue and cell manipulation, which employs a conceptually new conjugate surfaces flexure hinge (CSFH) silicon MEMS-based technology micro-gripper that solves most of the above-mentioned problems. The article describes all of the phases of the development, including topology conception, structural design, simulation, construction, actuation testing and in vitro observation. The latter phase deals with the assessment of the function capability, which consists of taking a series of in vitro images by optical microscopy. They offer a direct morphological comparison between the gripper and a variety of tissues.

Experimental Tests of the Operating Conditions of a Micro Gas Turbine Device

The aim of this work is to analyze the performance of a commercial micro gas turbine, focusing on the analysis of the fuel consumption and the outlet compressor and turbine temperature at various rpm, and to evaluate and compare the efficiency of the device. A test bench has been assembled with the available equipment in the laboratory of the department of mechanical and aerospace engineering in Roma. By using the software supplied by the manufacturer, the evaluation of the operating performance of the device at different speeds has been performed, obtaining all the values of interest.

The Gas Turbine Hybrid Vehicle LETHE™ at UDR1: The On-Board Innovative ORC Energy Recovery System — Feasibility Analysis

A GTHV (gas turbine hybrid vehicle) is an electric vehicle with traction entirely electric on 1 or 2 axles, equipped with a small turbogas whose only function is that of recharging the battery pack and possibly other energy storage devices present on board. After a brief review of the history of the GTHV technology, a complete feasibility assessment of a prototype configuration of a GTHV designed by the University of Roma 1 is presented. All issues related to the system and component design, packaging, identification of the “optimal” hybridization ratio, performance of the (gas turbine + batteries + electrical motor) conversion system, braking energy recovery systems (KERS), mechanical and electric storage devices (flywheels, capacitors, advanced batteries), monitoring and control logic, compliance with the European vehicular ECE emission regulations, have been already discussed in previous papers. The present study analyzes the feasibility to insert “on-board” an innovative and patented ORC (Organic Rankine Cycle) recovery system. In fact, the thermal source on the LETHE© vehicle is a turbogas of suitable power (10 to 30 kW depending on the vehicle class). The sensible heat of the exhaust gases is an ideal thermal source for an ORC system that can feed the car conditioning system and other auxiliaries.Copyright

The α-prototype of an ultra-micro-gas turbine at the University of Roma 1. Final assembly and tests

The paper describes the realization of the α-prototype of a portable power device consisting of an electrical generator with a power output of about 300 W driven by a small gas turbine set. The device is so small that it can be properly defined an ultra micro device, capable of supplying electric power in stand alone conditions and for prolonged periods of time (up to 24 hours continuously). In practice the device can be used as a convenient substitute (or replacement) for all current battery storage systems and is significantly smaller, lighter and most likely more reliable than the few existing internal combustion engines of comparable power output. The particular nomenclature is UMGTG-UDR1 (Ultra-Micro Gas Turbine Generator). The final configuration of the prototype (for which a patent is pending) is described in the paper as well, together with some of the results of the final operational tests.Copyright

Use of modified balje maps in the design of low reynolds number turbocompressors

The design of micro and ultra-micro turbomachinery introduces severe challenges due to the absence of a reliable and sufficiently extended database, so that the phenomenological differences among microturbomachines and between micro- and commercial-scale devices must be semi-empirically modelled from case to case. Scope of this study is to verify the possibility of extending the usual design correlations and maps to such small scales: specifically, this paper presents a procedure to conveniently modify the standard performance Balje map so that it can be adopted “as is” in the design of a micro and ultra-micro machines. The results of a systematic comparison with the general Stodola-like formula allow extending the applicability of Re-corrected Balje and Smith charts to the range of Re ≤ 10 5

The power generation with vegetable oils: A case study

The utilization of vegetable oils, and in particular the palm oil, as fuel in the power generation has had a remarkable development in the last few years. Generally the vegetable oil can be used with a particular marine-derived diesel ICE, with low rpm and an electric conversion efficiency of about 40%. The efficiency is strictly connected to the size of the plant. Moreover, the considerable amount of the required vegetable oil to feed the system forces to import the fuel. This is one of the most critical elements as the palm oil is subject to continuous and wide variations in prices. Due to this variation it is difficult to obtain a stable and convenient fuel supply over a long period of time. The present work is aimed at evaluating and estimating the economic, technical and environmental feasibility of a 20 MW plant for the stationary power generation fed with palm oil, enlightening the system solution (technical constructive aspects) and the economic appraisal, on the basis of variations in oil prices. Finally, the economic sensibility analysis based on the fuel cost and the European mechanisms of biomass incentives.

Preliminary Design of a Hybrid Propulsion System for High-Endurance UAV

In recent years, a renewed interest in the development of unmanned air vehicles (UAV’s) led to a wide range of interesting applications in the fields of reconnaissance and surveillance. In these types of mission, the noise produced by propeller driven UAVs is a major drawback, which can be partially solved by installing an electric motor to drive the propeller. The evolution of high performance brushless motors makes electric propulsion particularly appealing, at least for small and medium size UAVs. All electric propulsion systems developed to date are though characterized by the limited range/endurance that can be obtained with a reasonably sized battery pack. In this paper we propose a hybrid propulsion system based on recently developed, high efficiency micro-turbines which can be used to power an electric generator. The UMGT is under evaluation in our department, to achieve the optimal configuration and performances. For this scope a new compact regenerative combustion chamber has been developed and several tests has been carried out, with the aim to reduce weight and dimension and increase vehicle payload. In a high range/endurance mission the ultra-micro-turbine can provide the energy required for the cruise phase (the so-called “transfer to target”), while in the final approach, in which a quiet flight attitude is a demanding item, the battery pack drives the motor. The mission requirements adopted in the preliminary aircraft design presented here consist mainly of a long endurance (> 12 hours) step, with a cruise speed of 33.3 m/s and a dash speed of 45 m/s at an altitude of 5000 meters. The maximum take-off weight is 500 N, with a payload of 80 N. Under the above assumptions, a flying wing configuration for the UAV was defined, with a length of 1.6 meters and a span of 2.5 meters. A system of elevons assures the pitch and roll motion while a double vertical tail, in which a pusher propeller is lodged, guarantees the yaw stability and control.Copyright

Energy market impact of renewable energy source

New energy scenarios see renewable energy is no longer as marginal sources, but as actresses able to change the energy market. The past few years have seen the energy market more fluid than that of past decades, the constant growth of the renewable component of the global energy mix has changed the relationship between offer-demand and also because of the changing geopolitical conditions, there has been a constant reduced costs of fossil fuels. This article intends to put highlight, in Italian, as the market fossil fuels is influenced by the penetration of renewable energy. In addition, by relating the benefits (economic and externalities), obtained from the dissemination of renewable, with the costs for promoting the development of renewable energies.

A Small-Scale ORC Energy Recovery System for Vehicular Application: Feasibility Analysis and Preliminary Components Design

The paper analyses the feasibility of an “on-board” innovative and patented (patent ID RM2011 A 000671) ORC recovery system. The vehicle thermal source can be either a typical diesel engine (1400 cc) or a small gas turbine set (15–30 kW). The sensible heat recovered from the exhaust gases feeds the energy recovery system that can produce sufficient extra power to sustain the conditioning system and other auxiliaries. The concept is suitable for all types of thermally propelled vehicles, but it is studied here for automotive applications.The characteristics of the organic cycle-based recovery system are discussed, and a preliminary design of the main components, such as condenser, evaporator and pre-heater is presented. The main challenge are the imposed size and weight limitations that require a particular design for this compact heat exchangers. A possible system layout is analysed and the requirements for a prototypal application are investigated.At this stage of the project, no components costs evaluation is provided, in part because our scope is to demonstrate feasibility, and secondly most of the components are built in our own shop.Copyright

Experimental Tests on a Pre-Heated Combustion Chamber for Ultra Micro Gas Turbine Device: Air/Fuel Ratio Evaluation

Current portable power generators are mainly based on internal combustion engine since they present higher values of efficiency comparing to other engines; the main reason why internal combustion engine is not convenient for micro power generation (5 30 kW) is because of their heaviness. Micro and ultra micro gas turbine devices, based on a micro compressor and a micro turbine installed on the same shaft, are more suitable for this scope for several reasons. Micro turbine systems have many advantages over reciprocating engine generators, such as higher power density (with respect to size and weight), extremely low emissions and few, or just one, moving part. Those designed with foil bearings and air-cooling operate without oil, coolants or other hazardous materials. Micro turbines also have the advantage of having the majority of their waste heat contained in their relatively high temperature exhaust. Micro turbines offer several potential advantages compared to other technologies for small-scale power generation, including: a small number of moving parts, compact size, lightweight, greater efficiency, lower emissions, lower electricity costs, and opportunities to utilize waste fuels. The object of this study is the experimental tests on a stand-alone gas turbine device with a pre-heated combustion chamber (CC), to validate the fuel consumption reduction, compared to an actual and commercial device, used on air models.