A review of development of micro-channel heat exchanger applied in air-conditioning system

AbstractMicro-channel heat exchanger(MCHX) has been increasingly applied in HVAC&R(Heating, Ventilation, and Air Conditioning & Refrigeration) field due to its higher efficiently heat transfer rate, more compact structure, lower cost. The characteristics of micro-channel heat transfer and fluid dynamics are summarized in this paper. The methods about optimizations (ie, geometry and thermodynamic performance) and the advantages and disadvantages of the MCHX are analyzed

Variable Weighted Ordered Subset Image Reconstruction Algorithm

We propose two variable weighted iterative reconstruction algorithms (VW-ART and VW-OS-SART) to improve the algebraic reconstruction technique (ART) and simultaneous algebraic reconstruction technique (SART) and establish their convergence. In the two algorithms, the weighting varies with the geometrical direction of the ray. Experimental results with both numerical simulation and real CT data demonstrate that the VW-ART has a significant improvement in the quality of reconstructed images over ART and OS-SART. Moreover, both VW-ART and VW-OS-SART are more promising in convergence speed than the ART and SART, respectively

General spin systems without genuinely multipartite nonlocality

There are multipartite entangled states in many-body systems which may be potential resources in various quantum applications. There are lots of methods to witness specific entangled systems. However, no efficient method is available to explore many-body systems without multipartite entanglement. It may provide necessary restrictions for experimental preparations of multipartite entanglement. Our goal is to solve this problem for spin systems. The maximal effective velocity with propagation of information is bounded in quantum spin systems with short-range interactions from Lieb-Robinson's inequalities. This implies two clustering theorems for ground states and thermal states. With these propagation relations, we show that both the gapped ground state and thermal state at an upper-bounded inverse temperature have no genuine multipartite nonlocality when disjoint regions are far away from each other. The present $n$-particle system shows only biseparable quantum correlations when the propagation relations show exponential decay. Similar result holds for spin systems with product states as initial states. These results show interesting features of quantum many-body systems with exponential decay of correlations.Comment: 17 pages, 3 figure

QCD corrections to the R-parity violating processes ppˉ/pp→eμ+Xp\bar{p}/pp \to e\mu+X at hadron colliders

We present the QCD corrections to the processes $p\bar{p}/pp \to e\mu+X$ at the Tevatron and the CERN large hadron collider(LHC). The numerical results show that variation of K factor is in the range between $1.28(1.32)$ and $1.79(1.58)$ at the Tevatron(LHC). We find that the QCD correction part from the one-loop gluon-gluon fusion subprocess is remarkable at the LHC and should be taken into account.Comment: 7 pages, 6 Postscript figures, to be appeared in Phy. Rev.

Sleep-disordered breathing is associated with depletion of circulating endothelial progenitor cells and elevation in pulmonary arterial pressure in patients with decompensated systolic heart failure

BACKGROUND: Sleep-disordered breathing (SDB) is known to occur frequently in and may predict worsening progression of patients with congestive heart failure (CHF). SDB is also known to play an important role in the development of idiopathic pulmonary arterial hypertension (PAH) via inducing endothelial dysfunction and vascular remodeling, a pathological process that can be significantly influenced by factors such as osteoprotegerin (OPG) and endothelial progenitor cells (EPCs). The objective of this study is to determine if CHF with SDB is associated with changes in OPG, EPCs, and PAH. METHODS: EPCs were isolated, cultured, and quantified from CHF patients with SDB (n = 52), or without SDB (n = 68). OPG and N-terminal pro-brain natriuretic peptide (NT-proBNP) from each group was analyzed and correlated with EPCs and the mean pulmonary artery pressure (mPAP) measured by right heart catheterization. RESULTS: A significant decrease in circulating EPCs (29.30 ± 9.01 vs. 45.17 ± 10.51 EPCs/× 200 field; P < 0.05) was found in CHF patients with SDB compared to those without SDB. Both OPG (789.83 ± 89.38 vs. 551.29 ± 42.12 pg/mL; P < 0.05) and NT-proBNP (5946.50 ± 1434.50 vs. 3028.60 ± 811.90 ng/mL; P < 0.05) were also significantly elevated in SDB CHF patients who also had significantly elevated mPAP (50.2 ± 9.5 vs. 36.4 ± 4.1 mm Hg; P < 0.05). EPC numbers correlated inversely with the episodes of apnea and hypopnea per hour (RDI, r = -0.45, P = 0.037) and blood level of OPG (r = -0.53, P = 0.011). Although NT-proBNP was also increased significantly in patients with SDB, it had no correlation with either EPCs or RDI. CONCLUSIONS: SDB due to hypoxemia from decompensated CHF is associated with (1) OPG elevation, (2) EPC depletion, and (3) mPAP elevation. The inverse relationship of circulating OPG with EPCs suggests a likely mechanism for hypoxemia and OPG in the development of pulmonary vascular dysfunction via depleting EPCs, thus worsening prognosis of CHF