A computationally efficient simulation method for optimizing front contacts of concentrator multijunction solar cells

In this work, a novel multidiode model is proposed for optimizing the front grid of multijunction solar cells operating under concentration conditions. The model allows for quickly exploring the maximum achievable efficiency under a wide range of operating conditions and design parameters such as the redirecting capability, period and width of the fingers, the light concentration, and the metal and emitter sheet resistivity. The proposed multidiode model shows to be consistent with experimental data and with more complex modeling approaches such as the simulation program with integrated circuit emphasis (SPICE) model

Cyclic loading is harmful to articular cartilage from which proteoglycans have been partially depleted by retinoic acid

SummaryWe studied whether cyclic loading is harmful to degraded cartilage. Sets of four cartilage-bearing sesamoid bones were dissected from 5-year-old cows. One bone from each set was cultured for 17 h in control medium to serve as an ex vivo control. The three others were cultured for 1 week in control medium to which 0, 10 or 300 ng/ml retinoic acid (RAc), which depletes the cartilage matrix of proteoglycans, had been added. Two were then cultured for another week in control medium. During the last week, one of the two was subjected to a cyclic load (1 MPa, 0.2 Hz). Following treatment with RAc, glycosaminoglycan content and synthesis were significantly decreased, as confirmed by safranin O staining and autoradiography. They were further diminished by loading during the second week of culture. Increased amounts of 3-B-3(−) epitope were found in cartilage that had been treated with 300 ng/ml RAc and then loaded. While loading cartilage matrix that was only slightly degraded proved to be damaging, loading severely degraded cartilage matrix apparently induced osteoarthritic-like changes

Dammann Gratings for Local Oscillator Beam Multiplexing

In submillimetre-wave heterodyne imaging systems, optical coupling provides the most efficient way of combining local oscillator power with the array of signals from the telescope. For systems limited to one local oscillator source an ideal optical-coupling scheme would produce an array of appropriately scaled images of the local oscillator feed at the detectors without any loss in power. One candidate for a beam multiplexing system is the combination of an interferometric couple with a type of binary phase grating known as a Dammann grating. In this paper, we consider in some detail the feasibility of such a system