基于Deflation技术的预调制Restarted GMRES算法

电学层析成像的图像重建需要对逆问题进行求解,而求解过程中存在着非线性、欠定性以及病态性严重等难题,使得图像重建可能不收敛,或者致使收敛,但获得的图像分辨率较低。针对现有的一些图像重建算法,提出基于Deflation技术的预调制Restarted GMRES算法,在原有full GMRES算法基础上,提高了收敛速度以及图像成像分辨率,并通过仿真实验证明。

Tracking multiple targets in MIMO radar via adaptive asymmetric joint diagonalization with deflation

In view of the low performance of adaptive asymmetric joint diagonalization（AAJD）, especially its failure in tracking high maneuvering targets, an adaptive asymmetric joint diagonalization with deflation（AAJDd） algorithm is proposed. The AAJDd algorithm improves performance by estimating the direction of departure（DOD） and direction of arrival（DOA） directly, avoiding the reuse of the previous moment information in the AAJD algorithm.On this basis, the idea of sequential estimation of the principal component is introduced to turn the matrix operation into a constant operation, reducing the amount of computation and speeding up the convergence. Meanwhile, the eigenvalue is obtained, which can be used to estimate the number of targets. Then, the estimation of signal parameters via rotational invariance technique（ESPRIT） algorithm is improved to realize the automatic matching and association of DOD and DOA. The simulation results show that the AAJDd algorithm has higher tracking performance than the AAJD algorithm, especially when the high maneuvering target is tracked. The efficiency of the proposed method is verified.

Immediate balloon deflation method in endoscopic papillary large balloon dilation for extraction of difficult bile duct stones

Background/Aims: Recently, endoscopic papillary large balloon dilation (EPLBD) using a large balloon (12 - 20 mm) for extraction of difficult common bile duct (CBD) stones has been widely accepted with favorable outcomes. However, there is no consensus with regard to the ballooning time. The aim of our study was to evaluate the efficacy and safety of immediate balloon deflation in EPLBD for the treatment of difficult bile duct stone. Methods: This was a retrospective study of 80 consecutive patients with bile duct stones who were treated with an immediate balloon deflation method in EPLBD combined with endoscopic sphincterotomy (EST) between January 2010 and December 2012. Overall success rate, success rate at first ERCP, and the frequency of mechanical lithotripsy for complete stone removal were assessed for efficacy and safety was evaluated by assessing major complications. Results: Overall success rate for complete stone removal was high (78/80, 97.5%) and success rate for complete stone removal at first ERCP was 86.3% (69/80). The use of mechanical lithotripsy was 0% (0/80). The overall complication rate was favorable (5/80, 6.3%). PostERCP pancreatitis was observed in 3 patients (two: mild, one: moderate). In subgroup analysis, the presence of periampullary diverticulum was the only factor affecting the success rate at first ERCP. Conclusion: This study demonstrated the favorable outcome of immediate balloon deflation for treatment of difficult CBD stones and can be considered for clinical application.

A simple analytical method for deflation prediction of inflatable structures

The static performance of inflatable structures has been well studied and the dynamic deployment simulation has received much attention. However, very few studies focus on its deflation behavior. Although there are several dynamic finite element algorithms that can be applied to the deflation simulation, their computation costs are expensive, especially for large scale structures. In this work, a simple method based on classic thermodynamics and the analytical relationship between air and membrane was proposed to efficiently analyze the air state variables under the condition of ventilation. Combined with failure analysis of static bearing capacity, a fast incremental analytical method was presented to predict both elastic and post wrinkling deflation process of inflatable structures. Comparisons between simplified analysis, dynamic finite element simulation, and a full-scale experimental test are presented and the suitability of this simple method for solving the air state and predicting the deflation behavior of inflatable structures is proved.

Deflation rates of different clastic sediments in the arid regions of China

By wind tunnel experiment, we studied the deflation rates of 8 different clastic sediments in the arid regions of China, discussed the sources of aeolian sand and their influence on the development of sand dunes and formation of sand deserts from the view of dynamics of wind erosion. The average deflation rates of 8 typical clastic sediments in the arid regions of China can be arranged in the order of lacustrine sand 〉 alluvial sand 〉 weathered sandstone and shale 〉 pluvial sediments 〉 fluvioglacial sand 〉 weathered granite 〉 slope deposit 〉 glacial sediments. The deflation rates exhibited strong positive correlations with the erodible particle （0.063 2mm） content and sorting features. In contrast, the deflation rates had obvious negative correlations with the contents of silt clay （〈0.063 mm） and gravel （〉2 mm）. According to the deflation rates, the 8 typical clastic sediments can be divided into four categories： （1） lacustrine and alluvial sand, which are readily prone to wind erosion, assumed to be the main source of aeolian sand; （2） weathered sandstone and shale, pluvial sediments and fluvioglacial sand with considerable deflation rates, might be the secondary source of aeolian sand; （3） weathered granite and slope deposit having the lower deflation rates, could supply a little aeolian sand; and （4） glacial sediments with a strong anti-erodibility, could hardly offer any aeolian sand. In addition to the strong wind conditions, the exposure of extensive lacustrine sand induced by the desiccation of inland lake basin, as well as the pre-sorting of clastic sediments by flowing water should be the key factors influencing the development of sand deserts in China. The possible reason the sand deserts in China being mostly distributed around the inland lake basins and along riverbanks could be better understood through sand source analysis.

Deflation and Stock Prices

While the literature on inflation and stock prices is plentiful,there is little literature on deflation and stock prices.This paper explores the empirical data and makes a theoretical analysis of the likely impact on stock prices when expectations change from inflation to deflation.Deflation has a bad name among some economists and most investors.However,from a stock market perspective,deflations’bad name may not be well-deserved.Several observations support this:1)The 1930s was a statistical outlier and not representative for a deflationary period and deflation does not seem to create recessions,causality goes the other way;2)real stock returns are positive and around average in the periods leading up to and following the onset of deflation;3)when moving from low inflation to mild deflation,P/E ratios are virtually unchanged;and 4)peak P/E ratios seem to be reached at inflation rates close to zero.The author proposes three possible explanations for the seemingly disconnect between the empirical data and the“default”ex ante belief of most economists and investors:availability heurist,deflation illusion,and tax related issues in connection with the tax hypothesis.

Inflation, Deflation and Normal Price Adjustment

This paper thinks that the price of a commodity depends on both the value of the commodity and that of the currency. The change in either value will cause the change of the price of the commodity. Only the price rising caused by the decreasing of the currency value can be called inflation, and the price rising led by the increasing of the value of the merchandise can not be called inflation. Therefore, it is not proper, as defined by the modem economics, to think that any price increasing should be in general called inflation.

U.S.,not China, is culprit of global deflation, inflation

This paper is an outcome of comprehensive and systematic research on whether China exports deflation and inflation using the newly developed DAG technique. Our results indicate that in the international transmission of inflation, the United States, as the world's largest economy, plays a dominant role. In contrast, during both deflation and inflation periods, China has a minimal impact on the price levels of major trading partners. Thus China is not to be blamed for global deflation or inflation. This research has made use of DAG and some other techniques to yield reliable and reasonable conclusions.

Factorized Smith Method for A Class of High-Ranked Large-Scale T-Stein Equations

We introduce a factorized Smith method(FSM)for solving large-scale highranked T-Stein equations within the banded-plus-low-rank structure framework.To effectively reduce both computational complexity and storage requirements,we develop techniques including deflation and shift,partial truncation and compression,as well as redesign the residual computation and termination condition.Numerical examples demonstrate that the FSM outperforms the Smith method implemented with a hierarchical HODLR structured toolkit in terms of CPU time.

Avoiding the impact of deflation and deflation expectations on economic growth

This paper predicts that the Chinese economy will unlikely encounter inflation in the short term.The major risks posed to China currently are deflation and downward pressures.Macro-regulations should have a clear orientation,combining stable growth with prevention of deflation,and integrating demand-side regulation and supply-side structural reform.The focal point of the demand-side management is to set a reasonable bar for the growth rate of the economy and the rise of price levels in order to stabilize and guide market expectations.Policy makers should adopt a moderate and directional regulatory monetary policy,setting appropriate policy objectives for the prevention of deflation,as well as make use of a variety of policy measures.China should implement a structural fiscal policy in a proactive manner,giving extra dynamic ability to the implementation of policies so that they can be more effective.Afterwards,through a deep reform of the supply-side,China can reinforce economic restructuring and boost economic growth.Policy makers should pay close attention to the reform of key areas such as state-owned enterprises,land supply,finances,taxation,and prices.

Is China the Root Cause of Global Deflation?

The so-called" China exporting deflation”theory has been popular in the international businesscommunity recently. For example,international businessmagazines such as Us-based Business Week and Britainbased The Economist have discussed the topic of global deflation,in which the impact of floods of low-

Deflation and Structural Reform in China

BytheendofAugust1999,theRetailPriceIndex(RPI)inChinahascontinuouslydeclinedfor23monthsandtheConsumerPriceindex(CPI)declinedfor18months.Itisobviousthatthepressureofdeflationisgettingmoreserious.In1998,theRPIdecreased2.6percentandtheCPIfor0.8percent.In...

一种ARGB数据无损压缩解压算法的FPGA设计

提出了一种ARGB数据的无损压缩优化算法以及FPGA实现方法;为了避免对整个文件的解压和压缩,采用了Deflate算法的相关方法对图像按块进行压缩和解压,极大提高了存储器的访问效率;利用了Deflate算法对小块进行压缩,发挥了Deflate中LZ77压缩的Huffman压缩技术来优化压缩算法;通过VIVADO HLS将算法实现成FPGA电路,采用多张图片进行了实际应用,证实了算法的有效性,并分析了其功耗和时序信息。

Restarted Full Orthogonalization Method with Deflation for Shifted Linear Systems

In this paper,we study shifted restated full orthogonalization method with deflation for simultaneously solving a number of shifted systems of linear equations.Theoretical analysis shows that with the deflation technique,the new residual of shifted restarted FOM is still collinear with each other.Hence,the new approach can solve the shifted systems simultaneously based on the same Krylov subspace.Numerical experiments show that the deflation technique can significantly improve the convergence performance of shifted restarted FOM.

Using an ILU/Deflation Preconditioner for Simulation of a PEMFuel Cell Cathode Catalyst Layer

Numerical aspects of a pore scale model are investigated for the simulation of catalyst layers of polymer electrolyte membrane fuel cells.Coupled heat,mass and charged species transport together with reaction kinetics are taken into account using parallelized finite volume simulations for a range of nanostructured,computationally reconstructed catalyst layer samples.The effectiveness of implementing deflation as a second stage preconditioner generally improves convergence and results in better convergence behavior than more sophisticated first stage pre-conditioners.This behavior is attributed to the fact that the two stage preconditioner updates the preconditioning matrix at every GMRES restart,reducing the stalling effects that are commonly observed in restarted GMRES when a single stage preconditioner is used.In addition,the effectiveness of the deflation preconditioner is independent of the number of processors,whereas the localized block ILU preconditioner deteriorates in quality as the number of processors is increased.The total number of GMRES search directions required for convergence varies considerably depending on the preconditioner,but also depends on the catalyst layer microstructure,with low porosity microstructures requiring a smaller number of iterations.The improved model and numerical solution strategy should allow simulations for larger computational domains and improve the reliability of the predicted transport parameters.The preconditioning strategies presented in the paper are scalable and should prove effective for massively parallel simulations of other problems involving nonlinear equations.

基于上下文模型的超长哈夫曼码校正算法

常见的Gzip、Zlib数据压缩标准都采用Deflate协议压缩封装数据,Deflate协议中采用哈夫曼码编码源符号(Source symbols)。哈夫曼编码算法通过构建哈夫曼树生成哈夫曼码,Deflate协议限定源符号的哈夫曼码的码长不能超过最大值。源符号的哈夫曼码长最大值等于哈夫曼树的高度,因此当哈夫曼树的高度超过限定值时,需要先把哈夫曼树进行“校正”,随后再为每个符号分配。Gzip、Zlib软件参考代码中使用的基于二叉树搜索的“校正”算法,校正时需要遍历搜索哈夫曼树,寻找嫁接“节点”。校正流程时间消耗非常大,而且硬件实现难度较大。该文探索一种基于上下文模型校正超长哈夫曼树的算法,与参考二叉树搜索算法相比:该算法可以快速校正超长哈夫曼树,将校正的时间消耗降至为0,而且对压缩效果几乎没有影响(压缩比平均下降率仅为0.372%)。该算法也易于硬件化实现,可以实时校正超长哈夫曼码。

“通货紧缩”还是“物价收缩”,“通货膨胀”还是“物价膨胀”

中国将inflation翻译成通货膨胀是错误的,inflation所要表达的意思是"物价膨胀",物价全面持续过度上升这一客观现象用汉语来表达最恰当的词语也是"物价膨胀",而货币过度增加应称"货币膨胀"或"货币过多"。中国将deflation翻译成通货紧缩也是错误的,deflation所要表达的意思是"物价收缩",物价全面持续明显下降现象用一个概念概括最贴近的汉语词语是"物价收缩",而货币不敷需要直接称为"货币不足"更清晰。政策性减少货币供应量像是"通货紧缩",但直接称为"量化紧缩货币政策"更明确。把物价与"通货"、经济增长放在一个概念里会把理论搞乱。

基于图像平滑算法的电能质量数据压缩方法

为满足电能质量数据存储与传输的需要,基于图像平滑算法、二维离散小波变换以及图像多级树集合分裂编码算法提出了一种电能质量数据压缩新方法。将一维电能质量数据转换为二维矩阵以挖掘电能质量数据的循环间冗余性;应用数字图像平滑技术对二维变换后所得到的电能质量图像矩阵进行平滑处理以有利于二维小波变换编码;结合二维离散小波变换、图像多级树集合分裂编码以及DEFLATE编码算法对电能质量数据进行压缩。仿真实验结果表明,相对现有的电能质量数据压缩方法,所提出的方案不仅能更有效地压缩电能质量数据(同等压缩比的情况下,信噪比更高),而且还可以根据实际需求通过对压缩码率的控制灵活调节电能质量数据压缩性能。