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Stability of proteins in carbohydrates and other additives during freezing: the human growth hormone as a case study
No full textMolecular dynamics is here used to elucidate the mechanism of protein stabilization by carbohydrates and other additives during freezing. More specifically, we used molecular dynamics simulations to obtain a quantitative estimation of the capability of various cryoprotectants to preserve a model protein, the human growth hormone, against freezing stresses. Three mechanisms were investigated, preferential exclusion, water replacement, and vitrification. Model simulations were finally validated upon experimental data in terms of the ability of excipients to prevent protein aggregation. Overall, we found that the preferential exclusion and vitrification mechanisms are important during the whole freezing process, while water replacement becomes dominant only toward the end of the cryoconcentration phase. The disaccharides were found to be the most efficient excipients, in regard to both preferential exclusion and water replacement. Moreover, sugars were in general more efficient than other excipients, such as glycine or sorbitol
Design for green, mini radiosondes to track fluctuations along isopycnic surfaces in cloud environments
No full textAn introduction to innovative, bio-compatible, ultralight radiosondes that are aimed to be passively transported on isopycnic surfaces in cloud and clear air environments. Their goal is to track small-scale fluctuations of velocity, vorticity, temperature, humidity, acceleration and pressure for several hours within and outside the cloud boundary
On the discretization and application of two space-time boundary integral equations for 3D wave propagation problems in unbounded domains
No full textA performance assessment methodology for floating pitching WEC arrays
No full textThe advantage of producing energy via array of WECs and not via individual device has long been demonstrated [1]. The hydrodynamic analysis of wave energy converter arrays is relevant in productivity assessment. The goal of this work is to present an evaluation method of WECs' dynamic response in array configuration and the analysis of the disturbed wave field. A boundary element method (BEM) [2] has been adopted in order to identify the hydrodynamic coefficients of the WECs and to study the interaction between the single devices. The point absorbers' arrays have been widely studied and the interaction factor or q-factor has been introduced as performance index of the farm layout [3], [4]. In this study, the case of ISWEC device, Inertial Sea Wave Energy Converter [5], has been chosen. In order to compare the efficiency between an isolated device and a single device in a farm, the RAO on the pitch degree of freedom has been adopted as performance index. The linear approach, like BEM, has high limits of validity for the case of high amplitude oscillating systems. Therefore, a linearized pitch viscous damping term has been introduced in order to overcome the limits of the linear potential flow theory based methods
MODELLING IN-PLANE AND OUT-OF-PLANE RESPONSE OF INFILLED FRAMES THROUGH A FIBER MACRO-MODEL
No full textA new fiber macro-model for the simulation of combined in-plane and out-of plane response of infilled frames subjected to seismic actions is presented in the paper. The model consists of 4 pinned struts (two diagonals, one horizontal and one vertical) modeled with the nonlinear beam/column fiber-section elements available in OpenSees. The model is particularly suitable to predict the out-of-plane response as fiber-section elements can account for the coupling between axial load and bending moment occurring because of the arching mechanism developed by the infills beyond the first cracking. Moreover the model can account for the effect of the reciprocal damaging accumulated both in-plane and out-of-plane during shakings. The procedure for the identification of the struts is presented in the paper and is validated with experimental test data from different authors. The proposed model may be used as a computationally-light and effective tool for the assessment of the response of 3D structures subjected to ground motions acting in arbitrary directions
An Overview of Additive Manufacturing of Titanium Components by Directed Energy Deposition: Microstructure and Mechanical Properties
No full textThe directed energy deposition (DED) process can be employed to build net shape components or prototypes starting from powder or wires, through a layer-by-layer process. This process provides an opportunity to fabricate complex shaped and functionally graded parts that can be utilized in different engineering applications. DED uses a laser as a focused heat source to melt the in-situ delivered powder or wire-shaped raw materials. In the past years extensive studies on DED have shown that this process has great potential in order to be used for (i) rapid prototyping of metallic parts, (ii) fabrication of complex and customized parts, (iii) repairing/cladding valuable components which cannot be repaired by other traditional techniques. However, the industrial adoption of this process is still challenging owing to the lack of knowledge on the mechanical performances of the constructed components and also on the trustworthiness/durability of engineering parts produced by DED. This manuscript provides an overview of the additive manufacturing (AM) of titanium alloys and focuses in particular on the mechanical properties and microstructure of components fabricated by DED
Computer Engineers' Challenges for the Next Decade: The Triangle of Power Density, Circuit Degradation, and Reliability
No full textThis installment of Computer's series highlighting the work published in IEEE Computer Society journals comes from IEEE Transactions on Computers
Analysis & Modelling of Powertrain Components for an Efficient UAV Design
No full textIn the design of an unmanned aerial vehicle (UAV), one crucial problem is the flight autonomy of the overall system. The powertrain of electric UAVs, namely: battery, electronic speed controllers, motors and propellers has been analysed to evaluate their effect on the efficiency of the system, and thus the autonomy. Current literature and datasheets on UAV performances, especially on electric motor and propeller, are usually scattered and poor. Two different test benches have been developed to characterize speed controllers, motors and propellers; experimental results have been used to tune motor-propeller numerical models. The proposed work allowed to shade some doubts about the reliability of the available data and validate a model-based design methodology
Fifty Shades of Green; an empirical analysis of sustainable design approaches in fifty case studies of contemporary architecture
No full textIt is largely recognized that the world is facing fast changes in the environmental conditions, in the economic structure, and in the social dynamics. In this context, the fields of architecture and urban design have been evolving and reacting, by: addressing issues; proposing innovative design and technological solutions; and envisioning potential sustainable scenarios in a structured manner. Yet the debate around the value and the identity of the sustainability aesthetic is still open (Hosey 2012). Despite the complexity of this theoretical debate, the aesthetic of architecture and urban design has, in practice, already started to shift under the influence of economic, environmental and social sustainability principles. With the aim of shedding light on these changing dynamics, this paper proposes an empirical analysis to compare and contrast the aesthetic approaches of fifty case studies of recent buildings, which have been awarded with International sustainability prizes and/or with high score certifications by the major energy rating systems across countries. Specifically, the analysis will offer an interpretation of the relation between economic, social and environmental principles and the design solutions that were triggered by those concepts. The results of this analysis will show a remarkable variety of successful design strategies, as well as a number of design opportunities that yet need to be explored. The importance of this work is: to produce a set of statistic data that can contribute both to practice and to the theoretical debate on the aesthetic of sustainability, by providing examples of cause-effect relations between sustainability concepts and design solutions; as well as to understand and assist the changing dynamics of our built environment