Design and analysis of a new wave energy converter based on a point absorber and a hydraulic system harvesting energy from waves near the shore in calm seas

The aim of this paper is to illustrate the design of a new wave energy converter, composed of a point absorber and a hydraulic system (power take off) and sized for recovering energy in calm seas from waves near the shore. The point absorber is consisting of a rectangular shaped buoy integrating a piston pump. The set buoy‐pump oscillates under the waves action and moves natural water in a closed circuit hydraulic system (power take off) composed of a piping connecting the piston pump itself, a pressurized reservoir, a hydraulic turbine and a discharge tank. The methodology adopted for designing the main constituents involves a 1D mathematical model, settled for understanding the motion of the buoy under the hypothesis of regular waves and fully developed sea, and a sizing procedure applied for the design of all the components of the hydraulic system. The project related to the Calabrian site of Cetraro (Mediterranean Sea—south Italy) led to designing a system with a 4 m large buoy, associated with a small 13 cm diameter micro Pelton turbine, so that more than 22 000 kWh could be recovered in a year.     

Conceptual model-based design and environmental evaluation of waste solvent technologies: Application to the separation of the mixture acetone-water

In this paper, two waste solvent technologies are presented as alternatives to the disposal of spent acetone-water mixtures.

In the first alternative, a batch rectifier is used to concentrate the waste in order to obtain a distillate with a higher calorific value, which is then sent to off-site incineration either in a cement kiln or in a conventional waste solvent incinerator. The second alternative is a hybrid process composed by a batch rectifier and a pervaporation unit that processes in batchwise mode the first cut from the distillation task to obtain a dehydrated solvent. Here, four scenarios are considered, comprising two kinds of membrane materials and two different vacuum systems.

For each alternative, the conceptual design was carried out with the aid of conceptual models of the unit operations involved. Quasi-optimal values for design and operation variables were used as input data to perform an economical and an environmental assessment of each alternative. The economic analysis suggests that the hybrid process is the best alternative given that the replacement cost of fresh solvent (about 850 U$S/ton) is considered as a credit value.

From the environmental analysis with life cycle assessment, two main conclusions can be drawn: i) the use of the distillate as an alternative fuel in a cement kiln leads to a reduction in emissions that is relevant for the categories related to human health and ecosystem quality; and ii) in terms of resource depletion, the hybrid process distillation/pervaporation with the ceramic membrane HybSi (Pervatech) shows the lowest impact due to the solvent recovery.     

Exploitation of moderate wind resources by autonomous wind electric pumping systems

A laboratory test rig has been developed, in order to analyse the mutual interaction of the different components of a low power WEPS, in the presence of arbitrarily chosen wind intensity. The performances with moderate wind speed of a system composed by a horizontal axis, fixed-pitch wind turbine, a synchronous generator and a centrifugal electric pump have been investigated, both at the start and under steady-state conditions. A control strategy of the alternator field voltage, which facilitates the starting of the pump in the presence of modest wind intensity and maximises average water discharge under any wind condition, has been defined, implemented on an electronic board and tested.     

The influence of rotary valve distribution systems on the energetic efficiency of regenerative thermal oxidizers (RTO)

On–off valve systems, commonly used in regenerative thermal oxidizer (RTO) plants, generate, during the opening time, a mass flow rate (MFR) which is constant. On the contrary, rotary valve systems, which are increasingly adopted in RTO plants, are characterized by variable MFR profiles. In this work, the energy requirements of two RTO systems, equipped with on–off or rotary valves, were determined using a home‐developed numerical code. Energy performances were evaluated by calculating the thermal efficiency and pressure drop within structured or random packed bed RTO systems, at the same mean MFR. The results demonstrated that thermal efficiency was only moderately influenced by the valve system, and is slightly lower for the RTO with on–off valve. On the other hand, the study revealed that energy requirements of all RTO systems were basically unaffected by cycle duration, allowing valve rotational velocity to be freely set to maximize for other technical requirements. On the contrary, pressure drop was greatly influenced by the valve type and increased as variability in MFR function augmented. Moreover, the type of regenerator, structured or random packed bed, affected differently the total energy requirements (basically pumping energy plus auxiliary fuel). Energy requirements of structured and random regenerators were comparable only when volatile organic compounds concentration was lower than typical values encountered in the industrial practise. In other cases, structured regenerators RTO were more competitive. Finally, structured regenerators are usually the best choice when rotating valve distribution systems are adopted. Copyright © 2007 John Wiley & Sons, Ltd.     

Engineering Design Study on an Innovative Hydrokinetic Turbine with on Shore Foundation

Tidal currents are a resource of great potentiality and not yet fully explored. Several efforts have been made to exploit these resources, but the costs associated to the deployment of tidal plants in marine environments are usually too high. The aim of this work is to present a system able to handle with the above mentioned problems, through the development of a particular hydrokinetic turbine design. In previous works, the authors described a basic turbine configuration achieving interesting performances, although some operational inconveniences were detected. Those problems have been existing so the solution should be optimized and redesigned. As a result, a new design of the turbine is proposed, consisting of a double rotor spinning in opposite directions in order to balance the induced mechanical torque. From preliminary evaluations related to the Messina Strait tidal cycles （Punta Pezzo site, RC, Italy）, a single 12 m diameter turbine can supply a power of about 500 kW with a peak current speed of 3 m/s and deliver up to 450 MWh/year.     

Separation of stigmasta-3,5-diene, squalene lsomers, and wax esters from olive oils by single high-performance liquid chromatography run

To ascertain the authenticity of olive oils, the European Community Regulation requires the stigmasta-3,5-diene and wax ester contents to be determined. The official methods are time-consuming and not suitable for many daily analyses, as quality-control laboratories need. A method is presented here that allows single high-performance liquid chromatography separation of stigmasta-3,5-diene and wax esters, as well as of the squalene isomers, which give further information on the oil’s authenticity. For stigmasta-3,5-diene, the comparison with results obtained with the official method is good. Also for wax esters, the agreement was good, even if they were compared with results obtained from a quicker method as reliable as the official one. The possibility of separating the squalene isomers also at the same time makes the proposed method more advantageous. On the whole, the method, which is suggested for routine and quick screening but not for the exact evaluation of the analyte contents, seems to be a convenient choice for ascertaining on a daily basis the samples’ legal compliance (i.e., whether the analyte content is or is not below the legal value).     

Molecular Basis of the Anticancer and Antibacterial Properties of CecropinXJ Peptide: An In Silico Study

Esophageal cancer is an aggressive lethal malignancy causing thousands of deaths every year. While current treatments have poor outcomes, cecropinXJ (CXJ) is one of the very few peptides with demonstrated in vivo activity. The great interest in CXJ stems from its low toxicity and additional activity against most ESKAPE bacteria and fungi. Here, we present the first study of its mechanism of action based on molecular dynamics (MD) simulations and sequence-property alignment. Although unstructured in solution, predictions highlight the presence of two helices separated by a flexible hinge containing P24 and stabilized by the interaction of W2 with target biomembranes: an amphipathic helix-I and a poorly structured helix-II. Both MD and sequence-property alignment point to the important role of helix I in both the activity and the interaction with biomembranes. MD reveals that CXJ interacts mainly with phosphatidylserine (PS) but also with phosphatidylethanolamine (PE) headgroups, both found in the outer leaflet of cancer cells, while salt bridges with phosphate moieties are prevalent in bacterial biomimetic membranes composed of PE, phosphatidylglycerol (PG) and cardiolipin (CL). The antibacterial activity of CXJ might also explain its interaction with mitochondria, whose phospholipid composition recalls that of bacteria and its capability to induce apoptosis in cancer cells.     

Recognizing the orthography changes for identifying the temporal origin on the example of the Balkan historical documents

Neural Computing and Applications - This paper introduces a new approach for automatically identifying the temporal origin of the digitized historical documents stored as images on the example from...