State estimation of nonlinear systems is a challenging task, especially when the Gaussian approximation fails. The unscented Kalman filter was proposed to deal with state estimation of nonlinear systems. We modify the traditional unscented Kalman filter to capture the third-order moment (skewness) of the state vector. Methods are also proposed to reduce the computation time of the suggested approach, and showing that the proposed algorithm is as fast as the unscented Kalman filter. Simulation results confirm that the method is better than, or at least as good as, the unscented Kalman filter. 相似文献
There remains a vital necessity for new therapeutic approaches to combat metastatic cancers, which cause globally over 8 million deaths per year. Mesenchymal stem cells (MSCs) display aptitude as new therapeutic choices for cancer treatment. Exosomes, the most important mediator of MSCs, regulate tumor progression. The potential of harnessing exosomes from MSCs (MSCs-Exo) in cancer therapy is now being documented. MSCs-Exo can promote tumor progression by affecting tumor growth, metastasis, immunity, angiogenesis, and drug resistance. However, contradictory evidence has suggested that MSCs-Exo suppress tumors through several mechanisms. Therefore, the exact association between MSCs-Exo and tumors remains controversial. Accordingly, the applications of MSCs-Exo as novel drug delivery systems and standalone therapeutics are being extensively explored. In addition, engineering MSCs-Exo for targeting tumor cells has opened a new avenue for improving the efficiency of antitumor therapy. However, effective implementation in the clinical trials will need the establishment of standards for MSCs-Exo isolation and characterization as well as loading and engineering methods. The studies outlined in this review highlight the pivotal roles of MSCs-Exo in tumor progression and the promising potential of MSCs-Exo as therapeutic drug delivery vehicles for cancer treatment. 相似文献
A hydrogen liquefaction concept with an innovative configuration and a capacity of 4 kg·s-1 (345.6 t·d-1) is developed. The concept involves an ammonia absorption refrigeration system for the pre-cooling of hydrogen and MR streams from 25 ℃ to -30 ℃. The ammonia absorption refrigeration system is fed by exhaust gases of the Parand gas power plant that are normally dissipated to the environment with a temperature of 546 ℃. The simulation is performed by Aspen HYSYS V9.0, using two separate equations of state for simulating hydrogen and MR streams to gain more accurate results especially for ortho-para conversion. Results show that conversion enthalpy estimated by Aspen HYSYS, fits very well to the experimental data. Determining the important independent variables and composition of MRs are done using trial and error procedure, a functional and straightforward method for complicated systems. The minimum temperature limit in the cooling section is lowered, and an ortho-para converter is implemented in this section. The proposed concept performs well from energy aspects and leads to COP and SEC equal to 0.271 and 4.54 kW·h·kg-1, respectively. The main advantage of this study is in the low SEC, eliminating the losses of the distribution network, and improving the ability of the hydrogen liquefaction for energy storage in off-peak times. 相似文献
In this paper, a novel full-duplex overlay cognitive wireless powered communication network (FD-OCWPCN) is proposed where a full-duplex (FD) hybrid-access point (H-AP) supports the full access of all battery-free secondary users (SUs). The H-AP broadcasts wireless power to empower the nearby SUs in the downlink (DL) phase while decoding the information transmitted uplink (UL) phase by the SUs, simultaneously. To overcome the self-interference (SI) phenomenon in FD-OCWPCN, the problem of maximizing the system sum-throughput with optimal UL-DL transmission/reception time and H-AP’s transmit power allocation is considered. This problem is non-convex under perfect/imperfect SI cancelation (SIC), so we employ the active interference temperature control and the gradient projection techniques to effectively reduce it into a convex problem. Closed-form expressions for the perfect/imperfect SIC cases are also derived. To assess the performance of the FD-OCWPCN, a comparison with a half-duplex OCWPCN (HD-OCWPCN) is provided. The achievable average sum-throughput for different FD/HD-OCWPCN is compared in the context of the average and peak transmit power at the H-AP, the number of SUs, path loss exponent and fairness metric. The simulation results depict the superiority of the FD-OCWPCN over the HD-OCWPCN for the perfect SIC and the effective imperfect SIC.
A recent study indicated that negatively charged substances such as heparin and dextran sulfate accelerate thrombin activation of coagulation factor XI by a template mechanism. Because the serine proteinase of the natural anticoagulant pathway, activated protein C, can bind heparin, it was reasonable to think that these compounds may also bind protein C (PC) and accelerate its activation by thrombin or other heparin binding plasma serine proteinases by a similar mechanism. To test this, PC activation by thrombin and factor Xa (fXa) was studied in the presence of these polysaccharides. With thrombin in the absence of thrombomodulin (TM), these polysaccharides markedly reduced the Km for PC and Gla-domainless PC (GDPC) activation in the presence of Ca2+. With TM containing chondroitin sulfate, heparin did not influence PC activation by thrombin, but with TM lacking chondroitin sulfate, the characteristic high-affinity PC interaction at low Ca2+ (approximately 50 to 100 micromol/L) was largely eliminated by heparin. In EDTA, heparin enhanced thrombin activation of GDPC by reducing the Km, but it inhibited PC activation by increasing the Km. PC activation in EDTA was insensitive to the presence of heparin if the exosite 2 mutant, R93,97,101A thrombin, was used for activation. These results suggest that, when the Gla-domain of PC is not fully stabilized by Ca2+, it interacts with the anion binding exosite 2 of thrombin and that heparin binding to this site prevents this interaction. Additional studies indicated that, in the presence of phospholipid vesicles, heparin and dextran sulfate dramatically accelerate PC activation by fXa by also reducing the Km. Interestingly, on phospholipids containing 40% phosphatidylethanolamine, the activation rate of near physiological PC concentrations ( approximately 80 nmol/L) by fXa in the presence of dextran sulfate was nearly comparable to that observed by the thrombin-TM complex. The biochemical and potential therapeutical ramifications of these findings are discussed. 相似文献
Dissolution of commercial white fused and tabular Al2O3 grains into a model silicate slag was investigated after 1 h at 1450° and 1600°C. Formation of CA6 and hercynitic spinel layers was observed at all Al2O3/slag interfaces. The spinel layer was not always continuous, and so, compared with the CA6 layer, it had a less-significant effect on the dissolution process. The CA6 layer that formed adjacent to the tabular Al2O3 was incomplete at both temperatures, so that its dissolution was not a totally indirect process. These incomplete CA6 and spinel layers meant that slag penetrated into the tabular Al2O3 grains, which, thus, were corroded and disintegrated by the penetrating slag. There was evidence of liquid in the CA6 layer adjacent to the fused Al2O3 after 1 h at 1450°C, which also enabled direct dissolution. After 1 h at 1600°C, fused Al2O3 revealed a thick (∼60 μm), continuous and unpene-trated CA6 layer, indicating fully indirect dissolution at this temperature. 相似文献
Barium aluminate cements have been synthesized by barium carbonate, alumina, kaolin and colloidal silica as starting materials. The effects of the source of SiO2 and of firing temperature on phase formation and physical properties of the fired cements have been studied. Cement samples were characterized using XRD, SEM, EDX. The setting time and heat of hydration of cements were also evaluated. The barium aluminate cements were mixed in castables. Cold crushing strengths evaluated, and values compared to those obtained using calcium aluminate cement (Secar 71). Mixtures of BaCO3 and Al2O3 were targeted to produce BaAl2O4; which had fast set time, expansive behavior and lower strength compared to samples with SiO2 additions. SiO2 additions, regardless of source, resulted in BaAl2Si2O8 (celsian) formation. The prepared samples had short setting times and higher mechanical properties in comparison with standard calcium aluminate cement. 相似文献
In this study cellulose–nanohydroxyapatite composite was fabricated for bone tissue engineering applications. In this composite a natural biopolymer was reinforced with bioactive nanohydroxyapatite for replacement or healing of bone. The ionic liquid 1-n-butyl-3-methylimidazolium chloride (BmimCl) was used for dissolution of cellulose. 相似文献
An automated manufacturing system (AMS) is a complex network of processing, inspecting, and buffering nodes connected by system of transportation mechanisms. For an AMS, it is desirable to be capable to increase or decrease the output with the rise and fall of demand. Such specifications show the complexity of decision making in the field of AMSs and the need for concise and accurate modeling methods. Therefore, in this paper, a flexible jobshop automated manufacturing system is proposed to optimize the material flow. The flexibility is on the multi-shops of the same type and also multiple products that can be produced. An automated guided vehicle is applied for material handling. The objective is to optimize the material flow regarding the demand fluctuations and machine specifications. An illustrative example is presented to test the validity of the proposed mathematical model. 相似文献