A spectral selective lamellae concentrator system as BI-CPV/T System

In warm periods the excess of incoming solar energy into a greenhouse is more than required for the growth of the crop. In particular the near infrared radiation (NIR) part of the incoming radiation is not necessarily. In a previous research project a new type of greenhouse with an integrated concentrated photovoltaic system with thermal energy output (CPVT-system) was developed. This earlier system was based on a circular covering geometry and an integrated filter for reflecting the NIR of the greenhouse. The reflected radiation was used in a solar energy system. In this feasibility study the new CPVT-system is simplified so more economically by avoiding the asymmetric greenhouse construction with bended glass and the large construction for solar tracking. All parts of the solar concentrating system will be mounted inside a standard Venlo type greenhouse. The concentrator consists of lamellae which only focus the NIR-part of the spectrum onto the CPVT–module. This module is mounted to or integrated into the ridge or gutter of the greenhouse. With this spectral selection the heat load inside the greenhouse will be reduced. The target is a maximal total annual electricity production. The optimization is done with a ray tracing model fed with actual radiation data. Two types of lamellae are compared: flat lamellae and trough shaped lamellae which focus the radiation individually. Trough shaped lamellae have the advantage of reducing the number of lamellae in combination with a high concentration ratio. This will lower the costs for the servo drive of the lamellae. The reflected NIR radiation can be focused with a geometric concentration factor of 100x. The lamellae will not only reflect 49% of the NIR radiation but also a part of the whole solar spectrum. The total effective concentration ration factor will be 23x, including the transmission losses of the greenhouse and the efficiency of the concentrator. The high geometric concentration factor will limit the shadowing effect of the cultivation area by the PV-cells with only 1%. Further optimalisation in the energy yield were performed on determination of the optimal focal length of the trough shaped lamellae. The highest annual electrical output was found for lamellae with individual optimized focal lengths. In that case the annual output for Dutch climate conditions can be over 29 kWh/m

A Fresnel lenses based concentrated PV system in a greenhouse

The scope of this investigation is the development and testing of a new type of greenhouse with an integrated linear Fresnel lens, receiver module and an innovative system for tracking to exploit all direct radiation in a solar energy system. The basic idea of this horticultural application is to develop a greenhouse for pot plants (typical shadow plants) that do not like direct radiation. Removing all direct radiation will drastically reduce the need for cooling under summer conditions and the need for screens or lime coating of the glass to reflect or block a large part of the radiation. The removal of all direct radiation will block up to 81% of the solar energy, which will reduce the needed cooling capacity. The second measure is the integration of a solar energy system. When the (linear) Fresnel lenses are designed between double glass coverings and integrated in the greenhouse, the focused solar energy on the Thermal Photovoltaic (TPV) cell in the focus point delivers electric and thermal energy. The TPV module mounted in the focal point requires cooling due to the high heat load of the concentrated radiation (concentration factor of 50×). All parts are integrated in a greenhouse structure with a size of about 36 m2 and the electrical and thermal yield is determined for Dutch climate circumstances

A concentrator system for BI-CPVT with static linear Fresnel lenses

A greenhouse with Fresnel lenses in the south facing roof and a receiver for concentrated Photovoltaic with water cooling (CPVT system) will result in electrical and thermal energy output from the solar energy excess entering a greenhouse. The PV system converts about half of the direct radiation into heat and electricity. During periods with direct radiation this will significantly reduce the heat load on the greenhouse For an optimal performance the roof elements must be asymmetric with a steep inclination at the north side (the exact angle of course depends on the latitude of the building site). The Fresnel lens structure is best oriented in upwards direction. In the current design, two lenses are placed in the inner space of a double glass. This prevents pollution and condensation on the lenses. By the upward facing of the lens structure, the focus quality is preserved over a much broader range of angles of incidence compared to a lens with downward facing structures. Each PMMA lens with a size of 1.20m x 1.52m is composed of 12 ‘tiles’ for easy production. The focal distance of the lens is 1,875m and the geometrical concentration factor is 50×. This means that in most cases the focus line is thinner than 3 cm. The performance of the lens with respect to the shape of the focal area and the position of the focal line has been analyzed with ray tracing techniques. From this analyses and by the development of a smart tracking system only two motors can bring the receivers in the required positions. One motor controls the distance between lens and receiver and the other controls the translocation of the receivers parallel to the lens. The second conclusion was that the positions of the focal line are within the bounds of the greenhouse construction for almost the whole year. Only in winter, in the early morning and at the end of the day, the focal line will be unreachable. The light sum is very stable in the greenhouse compared with the light sum outside. The 480 m2 greenhouse, with the LCPVT system based on Static Fresnel lenses and a 12 m CPVT-module and a 200 m CT-module, is designed by Bode Project Engineering and constructed by Technokas in Bleiswijk the Netherlands. An electrical power of 37W/(m2 greenhouse) is measured at an incoming global radiation of 870 W/m² (on a horizontal plane). The fraction collected thermal yield is about 20% of the total incident direct radiation

Modelling Livestock Component in FSSIM

This document summarises the development of a ruminant livestock component for the Farm System Simulator (FSSIM). This includes treatments of energy and protein transactions in ruminant livestock that have been used as a basis for the biophysical simulations that will generate the input production parameters for FSSIM. The treatments are derived principally from the “French” feed evaluation and rationing system for protein and energy. Currently, we have constructed routines that are capable of simulating input-output relationships for energy and protein in the following representative systems; dairy cattle; suckler cows; growing and finishing cattle; sheep and goats. The calculations of energy and protein requirements for these classes of livestock are described in detail in this documen

Edge-preserving noise reduction in digital video sequences

In this paper an edge-preserving method for the enhancement of noisy sequences of pictures has been described and some experimental results have been reported. The experimental results give rise to the following remarks. Using the 5-point scale for picture quality, the method is able to restore noisy pictures of quality level 4 to a picture quality level 5 and of quality level 2 to quality level 4. For pictures with a very low SNR//i//n the method manages to make details, that were lost in the noise, recognizable

Compressibility effects in packed and open tubular gas and supercritical fluid chromatography

The influence of the pressure drop on the efficiency and speed of anal. in packed and open tubular supercrit. fluid chromatog. (SFC) is described: methods previously developed to describe the effects of mobile phase compressibility on the performance of open tubular columns in SFC have been extended to packed columns. The Horvath and Lin equation has been used to elucidate the influence of variations in velocity, diffusivity, and capacity factor along the column on the overall efficiency of packed column SFC. In packed columns, in contrast with the situation in open tubular columns, because the diffusion coeffs., the increase in both linear velocity and capacity factor which result from a significant pressure drop cause the plate height to increase along the column. The effect of liq. decompression along the length of the column on the speed of anal. in SFC has been studied and numerical expressions derived which enable calcn. of compressibility correction factors for the plate height. Both the f1 and f2 correction factors remain very close to unity for acceptable pressure drops, which means that the pressure drop has virtually no effect on the no. of plates generated per unit time for an unretained component. For retained species, the decompression of the mobile phase across the column causes the capacity factor to increase and hence leads to increased anal. time

Walking adaptability therapy after stroke: study protocol for a randomized controlled trial

Background: Walking in everyday life requires the ability to adapt walking to the environment. This adaptability is often impaired after stroke, and this might contribute to the increased fall risk after stroke. To improve safe community ambulation, walking adaptability training might be beneficial after stroke. This study is designed to compare the effects of two interventions for improving walking speed and walking adaptability: treadmill-based C-Mill therapy (therapy with augmented reality) and the overground FALLS program (a conventional therapy program). We hypothesize that C-Mill therapy will result in better outcomes than the FALLS program, owing to its expected greater amount of walking practice.Methods: This is a single-center parallel group randomized controlled trial with pre-intervention, post-intervention, retention, and follow-up tests. Forty persons after stroke (≥3 months) with deficits in walking or balance will be included. Participants will be randomly allocated to either C-Mill therapy or the overground FALLS program for 5 weeks. Both interventions will incorporate practice of walking adaptability and will be matched in terms of frequency, duration, and therapist attention. Walking speed, as determined by the 10 Meter Walking Test, will bethe primary outcome measure. Secondary outcome measures will pertain to walking adaptability (10 Meter Walking Test with context or cognitive dual-task and Interactive Walkway assessments). Furthermore, commonly used clinicalmeasures to determine walking ability (Timed Up-and-Go test), walking independence (Functional Ambulation Category), balance (Berg Balance Scale), and balance confidence (Activities-specific Balance Confidence scale) will be used, as well as a complementary set of walking-related assessments. The amount of walking practice (the number of steps taken per session) will be registered using the treadmill’s inbuilt step counter (C-Mill therapy) and video recordings (FALLS program). This process measure will be compared between the two interventions.Discussion: This study will assess the effects of treadmill-based C-Mill therapy compared with the overground FALLS program and thereby the relative importance of the amount of walking practice as a key aspect of effective intervention programs directed at improving walking speed and walking adaptability after stroke.Trial registration: Netherlands Trial Register NTR4030. Registered on 11 June 2013, amendment filed on 17 June 2016.Keywords: Exercise, Rehabilitation, Stroke, Therapy, Walking adaptability, Walking spee

The effect of shadow lines on a low concentrating photovoltaic system

In order to reduce the energy losses caused by shadow lines, three options are investigated. These are: 1. the use of two types of diodes; 2. the use of an ”ideal” diode based an active bypass by using MOS-FET’s [4] and 3. parallel switching of a number of cells between two shadow lines. The first method can reduce the voltage losses of the diode to about 300mV when oversized Schottky diodes are used. With the second method it is possible to reduce the voltage losses further to about 60mV for FETs with a resistance of 3m(omega). This method has as disadvantage that more electronic components are required to control the FET. With the third method about 10 cells are placed in parallel in one module. In that case only one shadow line appears on each module. Series connection of these parallel modules will result in zero energy losses because no bypass diodes are needed at all. This method has as a disadvantage of very high current output of the module of up to 200A. In a model, the three methods are further analyzed with respect of power losses and costs. The effect of the degree of shadowing on the daily energy yield and hence the fill factor is simulated with a model of the PV module. These results can be used in the design of the circuit of the ideal bypass diode

In silico analysis of the molecular machinery underlying aqueous humor production: Potential implications for glaucoma

Background: The ciliary body epithelia (CBE) of the eye produce the aqueous humor (AH). The equilibrium between the AH production by the CBE and the outflow through the trabecular meshwork ultimately determines the intraocular pressure (IOP). An increased IOP is a major risk factor for primary open angle glaucoma (POAG). This study aims to elucidate the molecular machinery of the most important function of the CBE: the AH production and composition, and aims to find possible new molecular clues for POAG and AH production-lowering drugs.Methods: We performed a gene expression analysis of the non-pigmented (NPE) and pigmented epithelia (PE) of the human CBE of post mortem eyes. We used 44 k Agilent microarrays against a common reference design. Functional annotations were performed with the Ingenuity knowledge database.Results: We built a molecular model of AH production by combining previously published physiological data with our current genomic expression data. Next, we investigated molecular CBE transport features which might influence AH composition. These features included caveolin- and clathrin vesicle-mediated transport of large biomolecules, as well as a range of substrate specific transporters. The presence of these transporters implies that, for example, immunoglobins, thyroid hormone, prostaglandins, cholesterol and vitamins can be secreted by the CBE along with the AH. In silico, we predicted some of the molecular apical interactions between the NPE and PE, the side where the two folded epithelia face each other. Finally, we found high expression of seven POAG disease genes in the plasma membrane of extracellular space of the CBE, namely APOE, CAV1, COL8A2, EDNRA, FBN1, RFTN1 and TLR4 and we found possible new targets for AH lowering drugs in the AH.Conclusions: The CBE expresses many transporters, which account for AH production and/or composition. Some of these entries have also been associated with POAG. We hypothesize that the CBE may play a more prominent role than currently thought in the pathogenesis of POAG, for example by changing the composition of AH