A dc arc faultdetection has been studied to improve the reliability of renewable energies and energy storage systems. In this Letter, the control algorithm of dc optimizer is proposed to detect the ...dc series arc fault condition between the PV panel and dc optimizer. The operational principle of the detection algorithm considers the characteristics of both the PV panel and arc fault, which can detect and extinguish the dc series arc fault condition. The validity of the proposed algorithm is verified through the simulation and experimental results.
Module-level power electronics can optimize the power generation of photovoltaic panels, which requires a simple topology structure, high power conversion efficiency, and wide voltage gain, ...corresponding to irradiance variations. This paper proposes a non-isolated current-fed L-C series resonant converter and its control algorithms. The proposed converter can obtain a buck–boost voltage gain with the hybrid control algorithm utilizing the switching frequency modulation and asymmetric pulse width modulation. The proper power stage design can guarantee the soft-switching capability for the entire operating range. Also, the control strategy is designed to obtain a small rms current. The operational principle of proposed converter is analyzed in order to design the resonant tank and control strategy. The performance of designed converter can be verified with the experimental results with a 500 W prototype converter.
Objectives
To summarize and compare unnecessary biopsy rates and diagnostic performance in the examination of thyroid nodules according to four representative US-based risk stratification systems.
...Methods
MEDLINE/PubMed and EMBASE databases were searched to identify original articles investigating unnecessary biopsy rates according to at least one of the following guidelines: ACR-TIRADS, ATA, EU-TIRADS, and K-TIRADS. The unnecessary biopsy rates for each risk stratification system were pooled using a random-effects model. Meta-regression analyses were performed to explore heterogeneity. Diagnostic odds ratios (DORs) for the appropriate selection of thyroid nodules for fine-needle aspiration were also pooled using a bivariate random-effects model.
Results
Eight articles including 13,092 thyroid nodules met the eligibility criteria and were included. The pooled unnecessary biopsy rates of ACR-TIRADS, ATA, EU-TIRADS, and K-TIRADS were 25% (95% CI, 22–29%), 51% (95% CI, 44–58%), 38% (95% CI, 16–66%), and 55% (95% CI, 42–67%), respectively. The pooled unnecessary biopsy rate of ACR-TIRADS was significantly lower than that of ATA (
p
< .001) and K-TIRADS (
p
< .001), and also lower than that of EU-TIRADS, but not reaching statistical significance (
p
= .087). The pooled DORs of ACR-TIRADS, ATA, and K-TIRADS were 5.9 (95% CI, 3.6–9.6), 6.3 (95% CI, 4.5–8.8), and 4.5 (95% CI, 1.7–11.6), respectively, with the differences not being statistically significant.
Conclusions
ACR-TIRADS showed a lower unnecessary biopsy rate than the other risk stratification systems albeit DOR was comparable between ACR-TIRADS, ATA, and K-TIRADS. Future revisions of each system should be made by referring to ACR-TIRADS to reduce unnecessary biopsy rates.
Key Points
• The pooled unnecessary biopsy rates of ACR-TIRADS, ATA, EU-TIRADS, and K-TIRADS were 25% (95% CI, 22–29%), 51% (95% CI, 44–58%), 38% (95% CI, 16–66%), and 55% (95% CI, 42–67%), respectively
.
• The pooled unnecessary biopsy rate of ACR-TIRADS was significantly lower than that of ATA (p < .001) and K-TIRADS (p < .001)
.
• The pooled DORs of ACR-TIRADS, ATA, and K-TIRADS were 5.9 (95% CI, 3.6–9.6), 6.3 (95% CI, 4.5–8.8), and 4.5 (95% CI, 1.7–11.6), respectively, with the differences not being statistically significant
.
In South Korea, a November 2021 outbreak caused by severe acute respiratory syndrome coronavirus 2 Omicron variant originated from 1 person with an imported case and spread to households, ...kindergartens, workplaces, restaurants, and hospitals, resulting in 11 clusters within 3 weeks. An epidemiologic curve indicated rapid community transmission of the Omicron variant.
Arc fault detection is an important process for ensuring the safety of PV and grid-connected inverters and is essential for producing PV systems in real applications. However, it is difficult to ...detect series dc arc faults using conventional fuses because these faults produce only small current variations. In addition, the arc fault detection devices have limited performance, because they focused on arc fault detection between PV arrays and inverter. Moreover, they require the additional current and voltage sensors to implement the arc fault detection algorithm. This article proposes an arc fault detection algorithm employing differential power processing (DPP) structure. The proposed algorithm only uses intrinsic voltage sensors of DPP and inverter, which can improve the cost-effectiveness of PV systems. In addition, the proposed algorithm can integrate the functionality of maximum power processing for each PV panel and arc fault detection. The voltage relationship between DPP and inverter is analyzed to detect the arc fault condition according to the DPP voltage sensing type. The performance of DPP units and its voltage relationship are verified with the control hardware-in-the-loop system. The arc fault detection performance is verified with the prototype PV system.
Objectives
To evaluate the safety and efficacy of balloon-occluded transcatheter arterial chemoembolization (B-TACE) for the treatment of HCC refractory to conventional TACE (C-TACE).
Methods
This ...single-center retrospective analysis included 60 consecutive patients who underwent B-TACE (mean age, 61.4 years; male:female ratio, 4.5:1) for the treatment of residual viable (
n
= 40) or recurrent HCC (
n
= 20) refractory to C-TACE between November 2017 and November 2018. Technical success, radiologic response rate (proportion of the patients achieving complete response CR or partial response PR on first follow-up CT according to m-RECIST), major complication rate, and time to progression (TTP) were evaluated. The TTP of B-TACE was also compared with that of the last C-TACE. Factors associated with achieving CR and TTP were explored.
Results
B-TACE resulted in 100% technical success and radiologic response rate (CR in 45 and PR in 15 patients). The major complication rate was 6.7% (4/60). The median TTP after B-TACE was 5.3 months (95% confidence interval CI, 4.0–6.9 months). The TTP of B-TACE for treating residual HCC was significantly longer than that of the last C-TACE (median 95% CI, 4.4 3.2–6.9 vs. 2.7 2.3–4.4 months;
p
= 0.013). BCLC stage C (adjusted OR, 4.448; 95% CI, 1.691–11.700;
p
= 0.002) and multiplicity of HCC (adjusted OR, 2.746; 95% CI, 1.206–6.251;
p
= 0.016) were significantly associated with tumor progression after B-TACE.
Conclusions
B-TACE is safe and effective for the treatment of HCC refractory to C-TACE. BCLC stage C and multiplicity of HCC were independent factors associated with TTP after B-TACE.
Key Points
• B-TACE for the treatment of HCC refractory to C-TACE showed a 100% radiologic response at first follow-up and a significantly longer TTP than the last C-TACE when treating residual tumor.
• The major complication rate after B-TACE was 6.7%. Although AST, ALT, and total bilirubin increase were more profound in B-TACE than in the last C-TACE, these were normalized at the first follow-up.
• Tumor size, multiplicity of HCC, and hepatic arterial injury were independent factors associated with achieving a complete response. BCLC stage C and multiplicity of HCC were significantly associated with TTP after B-TACE.
In this letter, a random-linear modulated spread spectrum technique for the induction heating (IH) appliances is proposed. The proposed method can effectively mitigate electromagnetic interference ...(EMI) emissions and can eliminate audible noises. Besides, it can suppress the total harmonic distortion (THD) compared with other modulations. The proposed random-linear modulation is evaluated by using a 1.8-kW IH prototype system. Experimental results verify the performance of EMI mitigation, audible noise elimination, and low THD using the proposed random-linear modulation compared with those of the conventional periodic and random modulations.
To determine optimal quarantine duration, we evaluated time from exposure to diagnosis for 107 close contacts of severe acute respiratory syndrome coronavirus 2 Omicron variant case-patients. Average ...time from exposure to diagnosis was 3.7 days; 70% of diagnoses were made on day 5 and 99.1% by day 10, suggesting 10-day quarantine.
Input parallel output parallel (IPOP) modular power converters have been used to supply high power and high current in various applications. In general, the IPOP modular power converter uses an ...output power balancing method to equally distribute the amount of output power to each converter. In this article, a hybrid input power balancing method is proposed to obtain high power conversion efficiency, high reliability, and enhanced dynamic performance of the IPOP modular power converters. In the steady state, the proposed method controls input power to be balanced in each converter. A power loss distribution capability of the input power balancing method can improve the entire power conversion efficiency and can reduce the overall operating temperature of the IPOP converters, which can increase lifetime and can improve reliability. During the transient operation, the proposed method makes the IPOP converters under an interleaving mode to tightly regulate the output voltage and to obtain fast dynamic performance. Experimental results with 200-W prototype modular synchronous buck converters verify the performance improvements of the proposed method such as high power conversion efficiency, the power loss distribution capability in the steady-state operation, and the enhanced dynamic performance in the transient operation.
A spread spectrum technique has been introduced to mitigate electromagnetic interference (EMI) in power converters. However, this technique is difficult to apply to resonant converters that use a ...pulse frequency modulation (PFM), because the spread spectrum can induce large output voltage fluctuations by PFM's switching frequency variations. In this letter, a hybrid control method using the PFM and phase shift modulation is proposed to obtain tight output voltage regulation under the spread spectrum operation of an LLC resonant converter. The performance of the proposed hybrid control method is experimentally verified using a 500 W prototype LLC resonant converter.
