A Linear Hybrid Concentrated Photovoltaic Solar Collector: A Methodology Proposal of Optical and Thermal Analysis

The photovoltaic cell surface in linear hybrid concentrated solar collectors receives non-uniform radiative flux, causing additional thermal stress due to hot spots and reducing its electrical performance and durability. The current study proposes a parametric methodology to determine the optimal receiver displacement required in a linear Cassegrain-type hybrid solar collector. The aim was to achieve a minimal non-uniformity distribution and a high radiative flux over the photovoltaic cells, considering optical errors close to real environment conditions and analyzing the heat transfer to determine the electrical and thermal efficiencies. The developed methodology was applied to analyze a case study with a receiver width of 0.125 m and rim angle of 80° and using a commercial silicon photovoltaic cell that supports up to 7000 W/m2. After applying the methodology, a hybrid solar collector with a concentration ratio of 13.0 and receiver displacement of 0.14 m is recommended. As a result, 5728 W/m2 of average radiative flux with non-uniformity lower than 4% was achieved. Thus, thanks to the proposed configuration, a low non-uniformity and high radiative flux were achieved, benefiting the photovoltaic cells’ life while improving their operation.

BER Performance Analysis of Non-Coherent Q-Ary Pulse Position Modulation Receivers on AWGN Channel

This paper introduces the structure of a Q-ary pulse position modulation (PPM) signal and presents a noncoherent suboptimal receiver and a noncoherent optimal receiver. Aiming at addressing the lack of an accurate theoretical formula of the bit error rate (BER) of a Q-ary PPM receiver in the additive white Gaussian noise (AWGN) channel in the existing literature, the theoretical formulas of the BER of a noncoherent suboptimal receiver and noncoherent optimal receiver are derived, respectively. The simulation results verify the correctness of the theoretical formulas. The theoretical formulas can be applied to a Q-ary PPM system including binary PPM. In addition, the analysis shows that the larger the Q, the better the error performance of the receiver and that the error performance of the optimal receiver is about 2 dB better than that of the suboptimal receiver. The relationship between the threshold coefficient of the suboptimal receiver and the error performance is also given.

Visible Light Communication with Input-Dependent Noise: Channel Estimation, Optimal Receiver Design and Performance Analysis

<div>In this paper, single-input single-output (SISO) visible light communication (VLC) subject to signal-dependent shot noise (SDSN) is investigated. We discuss both channel estimation and data transmission. In the former, we introduce least square (LS) and maximum likelihood (ML) estimators. Moreover, we derive the Cram´er–Rao lower bound (CRLB) of the channel estimation error. With regard to data transmission, we present optimal and sub-optimal receiver designs and discuss their bit error rate (BER) performance. In particular, a closed-form expression of the BER is derived for a sub-optimal receiver using the on-off-keying (OOK) modulation technique. An approximated expression is then derived for the optimal receiver. Our analysis shows that the CRLB performance does not have a linear relation with the SDSN, thermal noise, or the fading channel. On the other hand, the SDSN has a dramatic effect on the channel estimation error bound, and it can degrade the BER performance. Increased performance degradation can also be noticed due to the joint effects of the channel estimation error and SDSN.</div>

Visible Light Communication with Input-Dependent Noise: Channel Estimation, Optimal Receiver Design and Performance Analysis

<div>In this paper, single-input single-output (SISO) visible light communication (VLC) subject to signal-dependent shot noise (SDSN) is investigated. We discuss both channel estimation and data transmission. In the former, we introduce least square (LS) and maximum likelihood (ML) estimators. Moreover, we derive the Cram´er–Rao lower bound (CRLB) of the channel estimation error. With regard to data transmission, we present optimal and sub-optimal receiver designs and discuss their bit error rate (BER) performance. In particular, a closed-form expression of the BER is derived for a sub-optimal receiver using the on-off-keying (OOK) modulation technique. An approximated expression is then derived for the optimal receiver. Our analysis shows that the CRLB performance does not have a linear relation with the SDSN, thermal noise, or the fading channel. On the other hand, the SDSN has a dramatic effect on the channel estimation error bound, and it can degrade the BER performance. Increased performance degradation can also be noticed due to the joint effects of the channel estimation error and SDSN.</div>

Estimation of the Automated Video Control Device’s Target Functions Performance Probability

Operating quality of automated video control systems depends on optical specifications of video camera and peculiar features of video algorithm. Specified target function performance probability can serve as criterion of automated video control use efficiency. In this work, a new performance efficiency estimation method for automated equipment of target environment video control is suggested: to estimate the probability of target functions’ (object detection, capture, and auto tracking) performance. Theoretical prediction of target functions performance probability was built upon Johnson’s criterion and the use of optimal receiver model. The results of suggested method’s experimental verification have shown that target detection occurred when signal/noise ratio level was above 6. This level can be regarded as low value to ensure that object is detected with probability 0.9.

Point-of-care lung ultrasound predicts in-hospital mortality in acute heart failure

Summary Background B-lines have been associated with adverse clinical outcomes in patients with heart failure (HF) when found at hospital discharge or during outpatient visits. Whether lung ultrasound (LUS) assessed B-lines may predict in-hospital mortality in patients with acute HF is still undetermined. Aim To evaluate the association between B-lines on admission and in-hospital mortality among patients admitted with acute HF. Methods Hand-held LUS was used to examine patients with acute HF. LUS was performed in eight chest zones with a pocket ultrasound device and analyzed offline. The association between B-lines and in-hospital mortality was assessed using Cox regression models. Results We included 62 patients with median age 56 years, 69.4% men, and median left ventricle ejection fraction 25%. The sum of B-lines ranged from 0 to 53 (median 6.5). An optimal receiver operating characteristic-determined cut-off of ≥19 B-lines demonstrated a sensitivity of 57% and a specificity of 86% (area under the curve 0.788) for in-hospital mortality. The incremental prognostic value of LUS when compared with lung crackles or peripheral edema by integrated discrimination improvement was 12.96% (95% CI: 7.0–18.8, P = 0.02). Patients with ≥19 B-lines had a 4-fold higher risk of in-hospital mortality (HR 4.38; 95% CI: 1.37–13.95, P &lt; 0.01). Conclusion In patients admitted with acute HF, point-of-care LUS measurements of pulmonary congestion (B-lines) are associated with in-hospital mortality.