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Purpose: To evaluate the safety and effectiveness of endovascular treatment for massive hemoptysis caused by pulmonary pseudoaneurysm (PAP). Methods: The clinical data, imaging data, and endovascular treatment of 23 patients with massive hemoptysis caused by continuous PAP were retrospectively analyzed. The success, complication, postoperative recurrence rate, and influence of the treatment on pulmonary artery pressure were also evaluated. Results：Nineteen patients with bronchial artery (BA) or NBSA-PA fistula underwent bronchial artery embolization (BAE) + non-bronchial systemic artery embolization (NBSAE) + pulmonary artery embolization (PAE). The pulmonary artery (PA) pressures before and after embolization were 52.11±2.12 (35-69 cmH2O) and 33.58±1.63 (22-44 cmH2O), respectively (P=0.001). Four patients did not have BA or NBSA-PA fistula. Embolization was performed in two patients with distal pulmonalis lobar arteria PAP. Bare stent-assisted micro coil embolization was performed in the other two patients with PAP of main pulmonalis lobar arteria. The PA pressures of the four patients before and after treatment were 24.50±1.32 (22-28 cmH2O) and 24.75±1.70 (22-29 cmH2O), respectively (P=0.850). The technique had 100% success rate with no serious complications and a postoperative recurrence rate of 30%. Conclusion: Endovascular treatment is safe and effective for massive hemoptysis caused by PAP. The presence of BA or NBSA-PA fistula, BAE, or NBSAE can effectively reduce pulmonary hypertension.

To provide timely results for big data analytics, it is crucial to satisfy deadline requirements for MapReduce jobs in today’s production environments. Much effort has been devoted to the problem of meeting deadlines, and typically there exist two kinds of solutions. The first is to allocate appropriate resources to complete the entire job before the specified time limit, where missed deadlines result because of tight deadline constraints or lack of resources; the second is to run a pre-constructed sample based on deadline constraints, which can satisfy the time requirement but fail to maximize the volumes of processed data. In this paper, we propose a deadline-oriented task scheduling approach, named ‘Dart’, to address the above problem. Given a specified deadline and restricted resources, Dart uses an iterative estimation method, which is based on both historical data and job running status to precisely estimate the real-time job completion time. Based on the estimated time, Dart uses an approach–revise algorithm to make dynamic scheduling decisions for meeting deadlines while maximizing the amount of processed data and mitigating stragglers. Dart also efficiently handles task failures and data skew, protecting its performance from being harmed. We have validated our approach using workloads from OpenCloud and Facebook on a cluster of 64 virtual machines. The results show that Dart can not only effectively meet the deadline but also process near-maximum volumes of data even with tight deadlines and limited resources.

Friction and wear behavior exists between hoisting ropes that are wound around the drums of a multi-layer winding hoist. It decreases the service life of ropes and threatens mine safety. In this research, a series of experiments were conducted using a self-made test rig to study the effects of the strand lay direction and crossing angle on the winding rope's tribological behavior. Results show that the friction coefficient in the steady-state period shows a decreasing tendency with an increase of the crossing angle in both cross directions, but the variation range is different under different cross directions. Using thermal imaging, the high temperature regions always distribute along the strand lay direction in the gap between adjacent strands, as the cross direction is the same with the strand lay direction (right cross contact). Additionally, the temperature rise in the steady-state increases with the increase of the crossing angle in both cross directions. The differences of the wear scar morphology are obvious under different cross directions, especially for the large crossing angle tests. In the case of right cross, the variation range of wear mass loss is larger than that in left cross. The damage that forms on the wear surface is mainly ploughing, pits, plastic deformation, and fatigue fracture. The major wear mechanisms are adhesive wear, and abrasive and fatigue wear.

A key to obtain a high quality of stacking ensemble is to select a proper configuration for the specific dataset. Various approaches are proposed on this topic. GA-Ensemble is an effective approach using genetic algorithm to select the configuration. However, the weakness of the problem encoding and the reproduction of unnecessary individuals in GA-Ensemble impact the accuracy of the approach. In this work, the subspace partition and a tabu strategy are used to improve the accuracy of GA-Ensemble. The results over 13 UCI datasets show that the new proposed approach has a better performance.

The effect of the copper content on properties of electroless Ni-Cu-P coating on heat exchanger surface was investigated, such as adhesion strength and surface characteristic, and anti-fouling property, which were considered to mitigate the accumulation of mineral fouling in the heat exchangers. The electroless ternary Ni-Cu-P coatings with different copper content were prepared on mild steel (1015) substrate surfaces by adjusting process parameters. Surface morphologies of coating and adhesion strength were investigated by using scanning electron microscopy (SEM) and MFT-4000 multifunctional material surface performance instrument, respectively. The results showed that the adhesion strength was improved with the addition of copper in the coating. With the increase of copper content, the deposition rate of ternary Ni-Cu-P coatings was increased, and the boundary of nodular became obvious. Moreover, the surface free energy of ternary Ni-Cu-P coatings was increased with the increase of copper content in the coatings and then decreased when enhancing the copper content further. The further fouling experiments indicated that all the ternary Ni-Cu-P coating surfaces with different copper content inhibited the adhesion of fouling compared with the stainless steel surface. The adhesion weight of fouling was approximately in proportion with the copper addition of ternary Ni-Cu-P coatings, but not the value of surface free energy. The work provides evidence that both adhesion strength and anti-fouling ability should be combined to use when applying surface modification in the field of heat exchanger.

The purpose of the present study was to investigate the effect of the electroless Ni–Cu–P-PTFE deposit surface on anti-fouling of heat exchangers, which was considered as a way to mitigate the accumulation of mineral fouling in the heat exchangers. Electroless Ni–Cu–P-PTFE deposits with various PTFE content were prepared on mild steel (1015) substrate surface by different process parameters. Surface morphology and microhardness were investigated by using SEM, MH-6 Vickers, respectively. The results showed that the addition of PTFE particles into the Ni–Cu–P matrix hardly affected the microstructure of the deposits. Microhardness was decreased with the addition of PTFE in the deposits. Moreover, the surface free energy of Ni–Cu–P-PTFE deposits was decreased with the increase of PTFE particles in the deposits. Further fouling experiments indicated that the surfaces of Ni–Cu–P-PTFE deposits with different PTFE content inhibited the adhesion of fouling compared with the mild steel surface of the heat exchangers. The adhesion weight of fouling was approximately in inverse proportion with the addition of PTFE particles in the deposits, but not the value of surface roughnesss. The anti-fouling property can not be improved ideally even considering the option of making Ni–Cu–P-PTFE coatings smooth.

In distributed storage systems, erasure codes represent an attractive data redundancy solution which can provide the same reliability as replication requiring much less storage space. Multiple data losses happens usually and the lost data should be regenerated to maintain data redundancy in distributed storage systems. Regeneration for multiple data losses is expected to be finished as soon as possible, because the regeneration time can influence the data reliability and availability of distributed storage systems. However, multiple data losses is usually regenerated by regenerating single data loss one by one, which brings high entire regeneration time and severely reduces the data reliability and availability of distributed storage systems. In this paper, we propose a tree-structured parallel regeneration scheme based on regenerating codes (TPRORC) for multiple data losses in distributed storage systems. In our scheme, multiple regeneration trees based on regenerating code are constructed. Firstly, these trees are created independently, each of which dose not share any edges from the others and is responsible for one data loss; secondly, every regeneration tree based on regenerating codes owns the least network traffic and bandwidth optimized-paths for regenerating its data loss. Thus it can perform parallel regeneration for multiple data losses by using multiple optimized topology trees, in which network bandwidth is utilized efficiently and entire regeneration is overlapped. Our simulation results show that the tree-structured parallel regeneration scheme reduces the regeneration time significantly, compared to other regular regeneration schemes.

The massive data in Data centers network will be frequently accessed massive datasets for cloud services, which will lead to some new requirements and becomes an important issue for interconnection topology and data management in cloud computing. According to the cost-effective, the paper proposes a new interconnection network MyHeawood for cloud computing. MyHeawood is constructed by small switches and servers with dual-port NIC according to recursive method. The data placement strategy in MyHeawood is a hashing algorithm based on the family of hash functions. MyHeawood uses three replicas strategy base on master copy, which is allocated in different sub layer to improve the reliability of data.

With the rapid development of cloud computing, there are many storage structures have been proposed for satisfying cloud-based softwares requirements. Most existing distributed storage systems focus on a certain objective and only provide a certain storage structure. In this paper we present a novel block-level distributed storage system named Flex which integrates storage resource dispersed on the network into a whole one. Flex uses a device mapping framework to create dynamic and flexible storage structures for users. We have implemented the prototype and evaluated its performance; results show that Flex can provide a high performance in diverse storage structures.

A fast approach was described for the synthesis of water-dispersible monodisperse dopamine-coated Fe3O4 nanoparticles (DA-Fe3O4) with uniform size and shape via ligand-exchange of oleic acid on Fe3O4 using only 2 min. The prepared DA-Fe3O4 nanoparticles were characterized by transmission electron microscopy, Fourier transform infrared spectrometry, and vibrating sample magnetometer. The results indicated that the resulting DA-Fe3O4 nanoparticles had an average diameter of about 19.2 nm. The magnetic saturation value of the prepared DA-Fe3O4 nanoparticles was determined to be 72.87 emu/g, which indicating a well-established superparamagnetic property.

Spectrum trading is an important approach for the secondary users (SU, the unlicensed user) to share the spectrum resource with the primary users (PU, the licensed user). Such economic method can improve not only the efficiency but also the quality of spectrum sharing. For getting the most profit from the spectrum trading, we considered a spectrum trading model based on queueing theory. We analyzed the relationship between the spectrum server and the spectrum demander and discussed the problem of server uncertainty. Simulation results demonstrated the analysis results in terms of the idle probability and average queue size.

The ever-growing demand on information and data requires the efficient architecture for large-scale network storage systems. To serve very large scale applications, using inexpensive commodity becomes the common selection in nowadays cloud storage systems. Based on such unreliable hardware, building fault-tolerant mechanism is key issue to the system design. In this paper, we propose a rack-aware architecture for cloud storage systems.

In order to fully utilize the spectrum resource, dynamic spectrum access becomes a promising approach to increase the opportunity of spectrum access with the rapid development of cognitive radio. However the performance of cognitive radio networks (CRN) is considerably constrained by its limited power, memory and computing ability. Fortunately cloud computing, which is the highlight of current research, has the potential to make up for the disadvantages because of its vast storage and computing capacity. In this paper we will discuss the convergence of spectrum sharing and cloud computing from several aspects including model, advantages and challenges. A spectrum sharing model based on cloud computing (SSC) will be introduced.

In wireless cognitive networks the secondary users (SU, the unlicensed user) can share the spectrum via opportunistic access and spectrum trade. The former can’t offer the reliable and steady communication, while the latter can. It is a hot topic how the primary users (PU, the licensed user) provide the resources to SUs. We propose a novel spectrum trade model based on the Voronoi diagram: V-STM, which can promise fairness and rationality of spectrum lease. We also analyze the effect of communication range and price on spectrum trade. Simulation results demonstrate the performance of the proposed model in terms of the fairness of users and the whole profit of the network.

Various data-centric web applications are becoming the developing trend of information society. Cloud computing currently adopt column-oriented storage wide table to represent the heterogeneous structured data of these applications. The wide table reduces the waste of storage space, but slows down query efficiency. The paper implements the hybrid partition on access frequent (HPAF) to horizontally and vertically partition a wide table. It uses a variant of consistent hashing to dynamically horizontally partition a wide table across multiple storage nodes on each node’s performance; It use entropy to represent the number of reducing access data block from the table with N columns than from N column-oriented storage tables. According to the second law of thermodynamics, the paper designs an entropy increasing clustering algorithm to classify the columns of a wide table. The algorithm finds a cluster with multiple classes which save maximum access time. The paper implements an algorithm for structured query across multiple materialized views too. Lastly the paper demonstrates the query performance and storage efficiency of our strategy compared to single column storage.

In this study, Ni-P-SiC composite coatings were prepared by adding different amount of SiC particles into electroless Ni-P plating solution. The effects of SiC particles concentration in solution on depositing rate and composition of the coatings were investigated. The different SiC contents in coatings could be obtained by adjusting the amount of SiC particle concentration in electroless plating solution. Scanning electron microscopy (SEM) results indicate that SiC particles are dispersed in the composite coating and Ni-P alloy is mainly as a bond metal envelope with SiC particles. At the same time, the microhardness became increased and the wear resistance improved with the increasing of SiC content.

We are witnessing the rapid development of Cloud Computing techniques and services. Cloud Storage is widely applied in nowadays research and industry community. One of the most hottest topic in cloud storage is the data reliability. To ensure reliability under the condition of inexpensive hardware, several techniques are discussed and applied. We simplify and analyze the data reliability by a markov model, which includes the discussion of correlated failures and rack-aware placement. Our model aims to tell the effect of rack-aware placement for cloud storage systems.

In wireless cognitive radio networks (CRNs), user will send the sensing data to neighbors for spectrum allocation. Actually only part of data will affect the allocation result. The transmission of unused sensing data isn’t cost-efficient because it consumes a great deal of computing and network resource, especially for CRNs in which the spectrum and power resource is very precious. We propose an improving transmission availability algorithm— SkyChannel Query, which can find the non dominated channels and only transmit information of these channels. The experimental results show the advantages of our algorithm in terms of saving computing resource and improving transmission availability.

Data distribution is the basic behavior of P2P applications ( le sharing and stream- ing service) and it is a key element a ecting the performance of P2P systems. However, there are few research works that focus on data distribution of P2P applications from the view of whole system. In this paper we study the data distribution in P2P applications in terms of de- creasing the system distribution load. We de ne the distribution load of P2P systems formally and analyze how to decrease the system load quickly by means of mathematical analysis. More- over, we give a feasible fast distribution algorithm according to our theoretic conclusion. The experimental results show that our algorithm has signi cant improvement on data distribution speed and load balance.

The consistency problem is one of the key issues to determine system functionality and performance in DVE systems. The existing methods often cannot satisfy the requirements of order consistency and interval consistency at the same time, or impose a constraint relationship on receiver nodes which brings difficulties to optimize responsiveness. In this paper, we propose a novel interval consistency control method based on B-Tree data structure. The method can improve the overall responsiveness without compromising consistency functionality. Experimental results prove that our method can effectively improve the functionality and performance of DVE systems.

A wear tester was developed. MC PA (nylon) filled with MoS2 and PU (polyurethane) were used as the material of the rubber wheel of roller guide shoes. Their wear performances was investigated with the tester. The results show that the wear rate of MC PA increases firstly and then decreases with increasing load, and reverses with increasing velocity. The wear rate of PU decreases firstly and then increases with increasing velocity. In addition, the main wear mechanisms of PU are plough wear and abrasive wear at the low load (200N). At the loads of 200N~500N, the main wear form of MC PA is the adhesive wear. Adhesive wear is the main mechanism of MC PA at the low velocity (3m/s). Due to inner heat accumulation by friction, squama-peering occurs on MC PA surface at the high velocity (8m/s). The dominant wear mechanisms of PU are abrasive wear and fatigue pitting. And the main reason of PU’s failure is the interior heat accumulation caused by friction.

Ferrocene-functionalized polymers (poly(NIPAM/FCN)) and their β-CD (β-Cyclodextrin) complex have been prepared. The inclusion complexation between them was investigated by several techniques, including 1H NMR spectra, cyclic voltammetry, UV–vis spectra and dynamic light scattering measurements. The results showed that β-CD could interact with the reduced ferrocene side groups and hardly affect the oxidized form. Thus a redox-responsive inclusion complexation system based on β-CD and poly(NIPAM/FCN) was obtained. In addition, the effect of this inclusion complexation on the solution properties of this polymer was also investigated. LCST (lower critical solution temperature) increased and the viscosity decreased upon addition of β-CD into the reduced polymer solution due to the disruption of the hydrophobic interaction between the ferrocene side groups by the inclusion complexation. Yet LCST and viscosity of the oxidized polymer solution changed slightly, which resulted from the weak interaction exerted by ...

Copolymerizations of 1,3-pentadiene (PD) with 1,3-cyclopentadiene (CPD) initiated by aluminium trichloride were carried out in toluene. The addition of CPD in the PD polymerization system does not affect the molecular weight but greatly increases the softening point of the polymer due to the introduction of cyclic structures. The Gardner color scale of the polymer is also raised by introduction of unsaturated rings of CPD. The copolymerization gives a complete conversion but generates insoluble crosslinked gels at high CPD content due to the high crosslinking reactivity of CPD. The integral intensities of unsaturated protons from PD and CPD segments of the copolymer chain on the 1 H.NMR spectrum give a perfect correlation with the copolymer compositions. The low-conversion experiments were carried out with small amounts of CPD in order to determine the reactivity ratio in this copolymerization system (M 1 = PD and M 2 = CPD). The result of r 1 = k 11 /k 12 = 0.46 demonstrates that CPD has a higher reactivity than PD toward PD growing carbocations, and hence the copolymer shows a higher CPD proportion than the corresponding comonomer.

endo-Dicyclopentadiene (DCPD) was polymerized by various cationic initiating systems in different solvents. IR and 1H NMR results show that four types of structural units are formed due to the corresponding addition modes: the addition on the norbornenic (NB) double bond generates unit I and rearranged unit II, while the addition on the cyclopentenic (CP) double bond produces unit III and rearranged unit IV. The reaction medium has a stronger effect on the microstructure of the polymer (PDCPD) than initiating systems. The polymers prepared in toluene and n-hexane contain all four structural units, while the polymer produced in methylene chloride is composed of structural units II and IV. © 1996 John Wiley & Sons, Inc.

The polymerizations of 2-methyl-2-butene (2M2B) were carried out by various cationic initiators in different media at 30°C. All these polymerizations generate oily oligomers of rather low degrees of polymerization (3–5). Evidences from i.r. and 1H n.m.r. show that the oligomer chain contains structural units derived from both 2M2B and 2-methyl-1-butene (2M1B), which indicates that 2M2B isomerizes partially to 2M1B during the polymerization. The unsaturated endgroups also arise from chain transfers of both 2M2B and 2M1B growing carbocations by proton-elimination. The reaction carried out in toluene fails to produce any polymer or oligomer but generates an adduct of 2M2B and toluene by Friedel-Crafts alkylation.

Summary The cationic polymerization of 1,3-pentadiene (PD) initiated by A1C13 in n-hexane was carried out in the presence of allylic halides, i.e., 3-chloro-l-butene, allyl chloride, and allyl bromide. All these allylic halides strongly hindered crosslinking which is a major side reaction during PD cationic polymerization. Cyclization, another side reaction, was also reduced by the addition of the allylic halides. The influences of these halides on polymer yields and molecular weights are also discussed.

A kind of surfactants with a polymerizable end-group were synthesized. A nanometer polymer latex dispersion has been prepared in the presence of one of the above polymerizable surfactants. The latex particle size is in the range of 20–40 nm. An environmentally friendly water-based coating based on the above nanometer polymer latex dispersion has been prepared and the preparation process has been optimized. This water-based coating has been characterized and the results have shown promising properties comparable to the conventional solvent-based coatings.

Resume Les polymerisations du 1,3-pentadiene amorcee par le triflate d'aluminium (trifluoromethanesulfonate d'aluminium) ont ete etudiees en fonction de differents parametres (temperature, polarite, concentration en amorceur et concentration en monomere). Il a ete montre que la polymerisation etait possible a temperature ambiante (20°) et en milieu non polaire (hexane) aussi bien qu'en milieu polaire (CH2Cl2). Un mecanisme reactionnel a ete propose avec un coamorcage du a l'eau de cristallisation et/ou a l'acide triflique provenant de la synthese du triflate. Il a ete mis en evidence une reaction de transfert au polymere et des reactions de cyclisation intramoleculaire et de reticulation. Une etude de la reactivite des isomeres du pentadiene montre que l'isomere trans est plus reactif que l'isomere cis et ne donne que des enchainements 1,2 et 1,4. Par contre, l'isomere cis peut donner aussi des enchainements 3,4 et a une tendance plus grande a la formation de cycle.