Power Degradation Caused by Snail Trails in Urban Photovoltaic Energy Systems

AbstractIn recent years, a discoloration defect called as the snail trials emerged on crystalline silicon solar module in urban photovoltaic energy systems. It resulted in power degradation, and caused a serious concern about effects of this phenomenon on crystalline silicon solar modules, but very few publications have dealt with this phenomenon. In this paper, the crystalline silicon solar modules with snail trials are investigated by I-V and P-V characteristics, electroluminescence (EL) technique, thermography analysis, and energy production in photovoltaic power plant. The obtained results show that the snail trails may affect output of power for crystalline silicon solar modules compared with reference module, the energy production measured was about 9.1% lower than the normal array

Low voltage high-SNR pipeline data converters

design strategy is presented for obtaining high-SNR (14 bits or higher) in a low voltage pipeline data converter. This is accomplished with the removal of the S/H input stage and the use of a rail-to-rail input stage. The rail-to-rail input requires a reference calibration scheme to maintain converter linearity, and is implemented as a radix calibration

The Effectiveness and Safety of Manual Acupuncture Therapy in Patients with Poststroke Cognitive Impairment: A Meta-analysis

Background. Poststroke cognitive impairment (PSCI) is a common cause of disability among patients with stroke. Meanwhile, acupuncture has increasingly been used to improve motor and cognitive function for stroke patients. The aim of the present study was to summarize and evaluate the evidence on the effectiveness of acupuncture in treating PSCI. Methods. Eight databases (PubMed, The Cochrane Library, CNKI, WanFang Data, VIP, CBM, Medline, Embase databases) were searched from January 2010 to January 2020. Meta-analyses were conducted for the eligible randomized controlled trials (RCTs). Assessments were performed using Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), Barthel Index (BI), or modified Barthel Index (MBI). Results. A total of 657 relevant RCTs were identified, and 22 RCTs with 1856 patients were eventually included. Meta-analysis showed that acupuncture appeared to be effective for improving cognitive function as assessed by MMSE (mean difference MD=1.73, 95% confidence interval (CI) (1.39, 2.06), P<0.00001) and MoCA (MD=2.32, 95% CI (1.92, 2.73), P<0.00001). Furthermore, it also suggested that acupuncture could improve the activities of daily life (ADL) for PSCI patients as assessed by BI or MBI (SMD=0.97, 95% CI (0.57, 1.38), P<0.00001). Conclusions. Compared with nonacupuncture group, acupuncture group showed better effects in improving the scores of MMSE, MoCA, BI, and MBI. This meta-analysis provided positive evidence that acupuncture may be effective in improving cognitive function and activities of daily life for PSCI patients. Meanwhile, long retention time of acupuncture may improve cognitive function and activities of daily life, and twist technique may be an important factor that could influence cognitive function. However, further studies using large samples and a rigorous study design are needed to confirm the role of acupuncture in the treatment of PSCI

Low Voltage High-SNR Pipeline Data Converters

Abstract — A design strategy is presented for obtaining high-SNR (14 bits or higher) in a low voltage pipeline data converter. This is accomplished with the removal of the S/H input stage and the use of a rail-to-rail input stage. The rail-to-rail input requires a reference calibration scheme to maintain converter linearity, and is implemented as a radix calibration. I

Radix-based digital calibration technique for multi-stage ADC

Abstract—This paper describes a digital-domain self-calibration technique for multistage pipelined analog-to-digital converters (ADCs). By making the signal paths of both the input and the reference voltage the same, all error factors within a stage are merged into a single term which represents the equivalent radix number. The initially estimated radix for each stage mathematically iterates to the final correct value via an incremental update algorithm, after foreground calibration measurements are obtained during ADCs recycling mode of operation. In this way, an accurate calibration is achieved using a modified radix-based calculation. Two different single-bit-per-stage ADC adaptation/calibration methods are presented as examples. The proposed technique compensates for linear errors such as capacitor mismatches as well as finite opamp gain. Index Terms—Analog-to-digital converter (ADC), multistage ADC, pipelined recycling, radix-based digital calibration

0.9V 12mW 2MSPS Algorithmic ADC with 81dB SFDR

Abstract—An ultra low-voltage CMOS two-stage algorithm ADC incorporating background digital calibration is presented. The adopted low-voltage circuit technique achieves high-accuracy high-speed clocking without the use of clock boosting or bootstrapping. A resistor-based input sampling branch demonstrates high linearity and inherent low-voltage operation. The proposed background calibration accounts for capacitor mismatches and finite opamp gain error in the MDAC stages via a novel digital correlation scheme involving a twochannel ADC architecture. The prototype ADC, fabricated in a 0.18µm CMOS process, achieves 81dB SFDR at 0.9V and 2MSPS (12MHz clock) after calibration. The ADC operates up to 5MSPS (30MHz clock) with 4dB degradation. The total power consumption is 12mW, and the active die area is 1.4 mm 2. I

Serum Metabolic Characterization of Vitamin E Deficiency in <i>Holstein</i> Cows during the Transition Period Based on Proton Nuclear Magnetic Resonance Spectroscopy

Vitamin E, a potent antioxidant, is a necessary and complex micronutrient for cows. During the transition period, vitamin E deficiency (VED) is among the highest prevalent micronutrient deficits in dairy cows. It may eventually result in oxidative stress and immunological malfunction, and it increases the risk of peripartum disorders. At present, detailed data on blood metabolites in VED cows are limited. Consequently, the purpose of this research was to examine the alterations in the serum metabolic profile of VED cows throughout the early postpartum period. Using comprehensive 1H nuclear magnetic resonance (1H NMR), the alterations in serum metabolic activities of VED cows were analyzed. In total, 28 multiparous Holstein cows were assigned according to serum α-tocopherol (α-Toc) concentrations into normal (α-Toc ≥ 4 μg/mL, n = 14) and VED (α-Toc n = 14) groups at 21 days postpartum, and their blood samples were collected for biochemical and 1H NMR analyses. A t-test on independent samples as well as multivariate statistics were used to assess the findings. In comparison with normal cows, VED cows showed significantly worse body condition scores, milk yield, and dry matter intake (p p p > 0.05). Furthermore, 24 upregulated serum metabolites were identified under VED conditions. The metabolomics pathway analysis of these metabolites demonstrated that a global metabolic response to VED in cows was represented by changes in 11 metabolic pathways, comprising energy, carbohydrate, and amino acid metabolism. From these results, we conclude that VED cows were more likely to experience a negative energy balance characterized by alterations of common systemic metabolic processes and develop oxidative stress, inflammation, and ultimately liver injury. This study provides the first evidence of metabolic changes in cows with VED

A 0.9V 12mW 5MSPS algorithmic ADC with 77dB SFDR

Abstract—An ultra-low-voltage CMOS two-stage algorithm ADC featuring high SFDR and efficient background calibration is presented. The adopted low-voltage circuit technique achieves high-accuracy high-speed clocking without the use of clock boosting or bootstrapping. A resistor-based input sampling branch demonstrates high linearity and inherent low-voltage operation. The proposed background calibration accounts for capacitor mismatches and finite opamp gain error in the MDAC stages via a novel digital correlation scheme involving a two-channel ADC architecture. The prototype ADC, fabricated in a 0.18 m CMOS process, achieves 77-dB SFDR at 0.9 V and 5 MSPS (30 MHz clocking) after calibration. The measured SNR

Air-cavity dominated HCG-VCSEL with a wide continuous tuning

We present continuously tuned emission of 940-1000 mm wavelength from an electrically-pumped VCSEL without top DBR layers via an electrostatically controlled HCG mirror. Large tuning range results from a high optical intensity in the air cavity