Analysis of High Frequency Noise of Inverter Rotary Compressor

The inverter compressor driven by the inverter will cause high frequency noise, which will have adverse influence on total noise value and sound quality. In order to improve this problem, an existing compact rotary inverter compressor is studied in this paper. The influence law of inverter carrier wave of space vector pulse width modulation(SVPWM) technique on motor vibration and noise of compressor is analyzed and summarized. Combining order analysis and motor modal analysis, the results show that the high harmonic current induced by inverter carrier wave will produce high frequency electromagnetic force which excites the stator resonance, and finally results in high frequency noise of the compressor. Through optimization of the motor structure, the high frequency noise is reduced by more than 5dB(A), the sound quality is improved as well

Effect of disturbed coal pore structure on gas adsorption characteristics: mercury intrusion porosimetry

Studying pore structures of disturbed coal and their influences on adsorption characteristics is conducive to in-depth understanding of occurrence and migration of gas in reservoirs in areas prone to coal and gas outbursts. A mercury porosimeter and a high-pressure gas adsorption instrument were separately used to investigate pore structures and measure adsorption characteristics of disturbed coal and undisturbed coal in Ningtiaota Coal Mine and Xigu Coal Mine (Shaanxi Province, China). In addition, pore structures and gas adsorption characteristics of coal samples were studied. The Menger’s sponge model was adopted to calculate fractal dimensions of coal samples, to estimate influences of pore structures and fractal features on the gas adsorption characteristics of disturbed and undisturbed coal. Results show that the pore volume of undisturbed coal is mainly contributed by micropores and transitional pores, while that of disturbed coal arises mainly from macropores and mesopores. Micropores and transitional pores account for large proportions of the specific surface area of pores in both disturbed and undisturbed coal. The adsorption isotherms of disturbed and undisturbed coal conform to the Langmuir equation and tectonism increases the limiting adsorption quantity of coal. The fractal dimensions D1 of the four types of coal samples in the experiments are in the range of 2.7617–2.9961, while the fractal dimensions D1 and D2 of disturbed coal are both larger than those of undisturbed coal, indicating that disturbed coal is more likely to collapse under high pressure. The total pore volume, total specific surface area of pores, and fractal dimensions are positively correlated with the adsorption constant a, while they have U-shaped correlations with the adsorption constant b of coal samples. The adsorption constant a of disturbed coal is always greater than that of undisturbed coal, while no obvious trend is observed between the adsorption constant b and tectonism. The research results can provide theoretical basis for further study of gas occurrence in disturbed coal seams

Skin collagen advanced glycation endproducts (AGEs) and the long-term progression of sub-clinical cardiovascular disease in type 1 diabetes

BACKGROUND: We recently reported strong associations between eight skin collagen AGEs and two solubility markers from skin biopsies obtained at DCCT study closeout and the long-term progression of microvascular disease in EDIC, despite adjustment for mean glycemia. Herein we investigated the hypothesis that some of these AGEs (fluorescence to be reported elsewhere) correlate with long-term subclinical cardiovascular disease (CVD) measurements, i.e. coronary artery calcium score (CAC) at EDIC year 7-9 (n = 187), change of carotid intima-media thickness (IMT) from EDIC year 1 to year 6 and 12 (n = 127), and cardiac MRI outcomes at EDIC year 15-16 (n = 142). METHODS: Skin collagen AGE measurements obtained from stored specimens were related to clinical data from the DCCT/EDIC using Spearman correlations and multivariable logistic regression analyses. RESULTS: Spearman correlations showed furosine (early glycation) was associated with future mean CAC (p \u3c 0.05) and CAC \u3e0 (p = 0.39), but not with CAC score100. Glucosepane and pentosidine crosslinks, methylglyoxal hydroimidazolones (MG-H1) and pepsin solubility (inversely) correlated with IMT change from year 1 to 6(all P \u3c 0.05). Left ventricular (LV) mass (cMRI) correlated with MG-H1, and inversely with pepsin solubility (both p \u3c 0.05), while the ratio LV mass/end diastolic volume correlated with furosine and MG-H1 (both p \u3c 0.05), and highly with CML (p \u3c 0.01). In multivariate analysis only furosine (p = 0.01) was associated with CAC. In contrast IMT was inversely associated with lower collagen pepsin solubility and positively with glucosepane, CONCLUSIONS: In type 1 diabetes, multiple AGEs are associated with IMT progression in spite of adjustment for A1c implying a likely participatory role of glycation and AGE mediated crosslinking on matrix accumulation in coronary arteries. This may also apply to functional cardiac MRI outcomes, especially left ventricular mass. In contrast, early glycation measured by furosine, but not AGEs, was associated with CAC score, implying hyperglycemia as a risk factor in calcium deposition perhaps via processes independent of glycation. TRIAL REGISTRATION: Registered at Clinical trial reg. nos. NCT00360815 and NCT00360893, http://www.clinicaltrials.gov

New model-based bioequivalence statistical approaches for pharmacokinetic studies with sparse sampling

In traditional pharmacokinetic (PK) bioequivalence analysis, two one-sided tests (TOST) are conducted on the area under the concentration-time curve and the maximal concentration derived using a non-compartmental approach. When rich sampling is unfeasible, a model-based (MB) approach, using nonlinear mixed effect models (NLMEM) is possible. However, MB-TOST using asymptotic standard errors (SE) presents increased type I error when asymptotic conditions do not hold. Methods : In this work, we propose three alternative calculations of the SE based on i) an adaptation to NLMEM of the correction proposed by Gallant, ii) the a posteriori distribution of the treatment coefficient using the Hamiltonian Monte Carlo algorithm, and iii) parametric random effects and residual errors bootstrap. We evaluate these approaches by simulations, for two-arms parallel and two-periods two-sequences cross-over design with rich (n=10) and sparse (n=3) sampling under the null and the alternative hypotheses, with MB-TOST. Results: All new approaches correct for the in ation of MB-TOST type I error in PK studies with sparse designs. The approach based on the a posteriori distribution appears to be the best compromise between controlled type I errors and computing times. Conclusion: MB-TOST using non-asymptotic SE controls type I error rate better than when using asymptotic SE estimates for bioequivalence on PK studies with sparse sampling

Haptoglobin Genotype and the Rate of Renal Function Decline in the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications Study

Many patients with type 1 diabetes develop renal disease despite moderately good metabolic control, suggesting other risk factors may play a role. Recent evidence suggests that the haptoglobin (HP) 2-2 genotype, which codes for a protein with reduced antioxidant activity, may predict renal function decline in type 1 diabetes. We examined this hypothesis in 1,303 Caucasian participants in the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) study. HP genotype was determined by polyacrylamide gel electrophoresis. Glomerular filtration rate was estimated by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation and albumin excretion based on timed urine samples. Participants were followed up for a mean of 22 years. HP genotype was significantly associated with the development of sustained estimated glomerular filtration rate (GFR) \u3c60 mL/min/1.73 m2and with end-stage renal disease (ESRD), with HP 2-2 having greater risk than HP 2-1 and 1-1. No association was seen with albuminuria. Although there was no treatment group interaction, the associations were only significant in the conventional treatment group, where events rates were much higher. We conclude that the HP genotype is significantly associated with the development of reduced GFR and ESRD in the DCCT/EDIC study

Task-Oriented Semantic Communication with Semantic Reconstruction: An Extended Rate-Distortion Theory Based Scheme

Compressed semantic representation of source is essentially important to accomplish various artificial intelligent (AI) tasks in task-oriented semantic communication (TOSC). In this paper, by extending the rate-distortion theory to multiple tasks, we propose a TOSC scheme with semantic reconstruction (SR), named as TOSC-SR, in the joint source and channel coding (JSCC) framework. Besides extracting and compressing task semantics, our basic idea here is to reconstruct images with task semantics rather than traditionally in the pixels or features. The main purpose is to share the semantic-reconstructed images among multiple tasks with enhanced generalization ability under certain rate. We formulate the TOSC-SR scheme as a rate-distortion optimization problem, where a novel semantic distortion measurement is defined by mutual information of source, the semantic-reconstructed images, and task labels, pairwise. We derive an analytic solution for the formulated problem, where the self-consistent equations are obtained to determine the optimal mapping of source and the semantic-reconstructed images by taking task labels into account. In the TOSC-SR scheme which is feasible in practice, a relaxed version of loss function is derived based on variational approximation of mutual information. Then we adopt the classification task to train TOSC-SR, and the object detection task to validate the generalization ability. Experimental results show that the proposed TOSC-SR scheme outperforms conventional JPEG, JPEG2000 based communication schemes and deep learning based TOSC with general reconstruction schemes in terms of reconstruction quality, classification and object detection performance at the same source compression ratio and signal-to-noise (SNR) regime.Comment: 18 pages, 10 figure