基于单水平集的多目标轮廓提取

多目标轮廓提取是图像分割的重要研究内容.文章在Chan和Vese的无边界主动轮廓模型(简称CV模型)的基础上,提出基于单水平集的多目标轮廓提取算法.CV模型只能实现单目标的轮廓提取,主要原因是不能使水平集函数驱动的轮廓线在某些目标区域正确分裂,没有有效利用轮廓线的拓扑分裂信息.通过修正CV模型,引入标记模板,用于追踪零水平集的分裂情况,对不同的准目标区域区别处理;引入图像区域均值模板,用于估计可能淹没在背景区域中的目标区域,促使水平集函数在上述目标区域充分变形,使对应零水平集充分分裂,实现多目标轮廓提取.并且文章提供了一系列不同条件下的实验结果,并与其它类似的研究成果进行比较,结果表明,该文的工作是有意义的.

具有部分多目标轮廓提取特性的单水平集方法

C-V模型只能实现单目标图像的轮廓提取,造成这种后果的主要原因是C-V模型过多地考虑了演化曲线内外部的信息,反而造成了曲线的不正确演化。针对这点,提出了一种新的更为简单的水平集方法,该方法对初始曲线位置选取没有特殊要求,演化过程中符号距离函数也无需重新初始化。运用该方法,给出了几幅不同性质图像的实验结果,结果表明,方法不仅能保证单目标轮廓的正确提取,还具有部分多目标轮廓提取的特点,而且需时少,具有一定的抗噪性。

二维平衡单水平轮换模式设计研究

现行的轮换样本调查使用各种类型的单水平轮换模式,在西方各国均得到了广泛应用,但是也存在着一系列问题。因此,通过对各种类型的轮换模式进行统一,并进行系统化、理论化研究,最终得出了二维平衡单水平轮换模式设计方法,并对其应用优势进行了总结。这套设计方法不仅将轮换模式设计与后续的估计方法研究统一起来,而且还能够削减各类轮换偏差的负面影响,并能准确度量轮换样本之间的相关关系,最终得出更加准确的连续性抽样估计量。

基于多阈值单水平集方法的医学图像分割

针对Chan-Vese的无边界主动轮廓模型(CV模型)只能区分前景与背景的缺点,提出了一种基于多阈值单水平集的医学图像分割方法,并将此方法应用于微创手术的预处理中。由于医学图像结构复杂,具有器官轮廓多连接等特点,因此使用常规的水平集方法进行分割往往不能取得理想的效果,而该方法采用修改目标泛函的方式引入多类分割,具有多区域分割的特点,只需经过一次单水平集的迭代循环,即可将图像根据灰度不同划分为多个区域,具有精确、快速等优点。对不同的合成图像和医学图像的实验结果表明,该方法实现了快速精确的多区域分割,能很好地提取到医学图像中的骨骼轮廓,分割效果达到了预期水平。

单水平连续性抽样方案CSP-V的流向图方法

本文利用转移概率流图和转移概率母函数的方法推导并得到了连续性抽样方案CSP—V的平均检出质量 (AOQ)、平均检查比离 (AFI)、和操作特性函数 (OC)

控制单水平研究中的多水平误差:基于设计的方法

由于取样设计的原因,多水平数据结构不仅存在于多水平研究,也广泛存在于单水平研究,需要在单水平分析中控制多水平误差。此时使用多层线性模型发挥不了优势,反而因模型的复杂性带来麻烦。基于设计的方法相对更简单、高效和稳健,更契合含多水平误差的单水平研究情境。在详细介绍基于设计的方法及其优势后,利用数据实例展示基于设计的方法在单水平研究中控制多水平误差的效果,并为应用研究者提供方法选用建议。

基于羽毛球的水平集分割方法应用

该文主要论述了利用双水平集C-V模型对羽毛球图像进行了分割,并且与单水平集C-V模型进行了比较,提出了图像中感兴趣的部分,实质就是采用多个水平集函数将图像划分多种类区域的分割模型。仿真结果表明了该分割方法的可行性。

自然崩落法放矿方案初步优化

放矿方案优化是放矿优化控制和放矿管理的基础。以数字矿山软件平台和VC++为工具,进行自然崩落法放矿方案优化研究。首先确定放矿方案构成要素与放矿方案优化准则;在数字矿山软件平台上构建放矿优化三维模型,确定放矿水平及放矿边界;自动确定放矿结构参数及布置放矿点,建立放矿点和放矿分层的品位计算数据搜索模型,通过品位估值确定放矿点及放矿分层的品位分布;建立基于矿山利润的放矿资源价值模型,以金属市场价格、生产成本及贫损指标为基础输入参数,计算各放矿分层的价值和利润,得到放矿点的最佳放矿高度、担负矿量和出矿截止品位,从而确定放矿优化方案,并为放矿计划编制和管理提供数据。

轮换样本调查的轮换模式设计与估计方法

文章以我国城市住户调查的轮换模式设计为例,研究了轮换样本调查中的轮换模式设计与估计方法等问题。不完全单水平轮换模式是轮换样本调查中非常理想的一种轮换模式,既吸收了单水平轮换模式的优点,又充分体现了轮换样本调查的优势。文章所研究的这套轮换模式设计与估计方法不仅适合在我国城市住户抽样调查中使用,而且也可推广应用到我国政府统计部门开展的其他类型的连续性抽样调查中。

不同海拔下无创呼吸机性能测试研究

目的:探究无创呼吸机通气性能与海拔高度变化的关系。方法:首先将6台不同型号的无创呼吸机(包括2台单水平呼吸机和4台双水平呼吸机)连接好气体质量流量计和夹板模拟肺后放置在低压舱中,然后使用低压舱分别模拟0、1500、3000、4500、6000 m海拔高度的气压环境进行测试。2种呼吸机通气均设置高输出气压组和低输出气压组,对于单水平呼吸机,呼吸机模式设置为持续气道正压通气(continuous positive airway pressure,CPAP),高输出气压组CPAP设置为20 cmH_(2)O(1 cmH_(2)O=98.06 Pa),低输出气压组CPAP设置为8 cmH_(2)O;对于双水平呼吸机,呼吸机模式设置为同步/时间(spontaneous/timed,S/T)模式,高输出气压组呼气相气道正压(expiratory positive airway pressure,EPAP)和吸气相气道正压(inspiratory positive airway pressure,IPAP)分别设置为10、20 cmH_(2)O,低输出气压组EPAP和IPAP分别设置为4、8 cmH_(2)O。在不同模拟海拔下记录气体质量流量计显示的输出气压值数据。结果:实验结果表明,随着海拔的升高,呼吸机实际输出气道正压均呈下降趋势,双水平呼吸机较单水平呼吸机下降幅度更大,且高输出气压组相比低输出气压组下降幅度更为明显,EPAP相比IPAP下降幅度更为明显。结论:该研究可为不同海拔地区的医护人员在使用呼吸机前对相应的参数设置做出修正调整提供参考,还可为呼吸机厂商在呼吸机高海拔补偿功能研发方面提供实验数据。

随机截距潜在转变分析(RI-LTA)--个案自我转变与个案间差异的分离

传统的潜在转变分析属于单水平分析,但其同样也可以看作二水平分析。Muthén和Asparouhov就以二水平分析的视角在单水平分析框架内提出了随机截距潜在转变分析(RI-LTA),其中跨时间点产生的自我转变可以看作在水平1进行分析,跨时间点不变的个案间差异可以看作在水平2进行分析,使个案的自我转变和个案间的初始差异分离,避免了高估保留在初始类别的概率。某研究型大学2016级本科生的追踪调查数据被用于演示使用随机截距潜在转变分析的过程。该方法的最大优势是通过引入随机截距避免了高估保留在本类别的转变概率。未来研究可以运用蒙特卡洛模拟研究探究随机截距潜在转变分析模型的适用性,也可以用多水平分析的思路为灵感,探究多水平随机截距潜在转变分析在统计软件中的实现。

不同无创气道正压通气对老年重叠综合征患者炎症因子的影响

目的探讨双水平气道正压通气(BIPAP)与单水平持续气道正压通气(CPAP)对老年重叠综合征(OS),即阻塞性睡眠呼吸暂停低通气综合征(OSAHS)合并慢性阻塞性肺疾病(COPD)患者炎症因子的影响。方法选取2016年6月~2020年1月解放军总医院第六医学中心收治的老年重度OSAHS合并轻中度稳定期COPD患者122例,根据随机数表分为BIPAP组与CPAP组,各61例。分别监测治疗前与治疗后3周呼吸暂停低通气指数(AHI)、呼吸暂停时间、夜间平均血氧饱和度(M-SaO_(2))、夜间最低血氧饱和度(L-SaO_(2)),炎症因子白细胞介素-33(IL-33)、可溶性基质裂解素(sST2)、肿瘤坏死因子-α(TNF-α)、内皮素-1(ET-1)等指标的变化。结果治疗后,两组患者AHI、呼吸暂停时间均较治疗前降低,M-SaO_(2)、L-SaO_(2)均较治疗前升高,差异有统计学意义(P<0.01)。且治疗后BIPAP组AHI、呼吸暂停时间下降程度明显优于CPAP组[(10.95±2.81)vs.(12.18±2.98)、(15.93±6.97)s vs.(18.92±7.23)s],M-SaO_(2)、L-SaO_(2)升高优于CPAP组[(94.82±12.69)%vs.(90.01±13.97)%、(89.56±11.13)%vs.(85.70±10.25)%],差异有统计学意义(t=2.35、2.33、1.99、1.99,P<0.05)。治疗后,两组患者IL-33、sST2、TNF-α、ET-1均较治疗前降低,差异有统计学意义(P<0.01)。且治疗后BIPAP组IL-33、sST2、TNF-α、ET-1下降程度明显优于CPAP组[(30.27±4.97)pg ml vs.(32.01±5.51)pg ml、(0.57±0.19)ng/ml vs.(0.62±0.17)ng/ml、(31.31±6.07)pg ml vs.(33.54±5.11)pg ml、(46.99±7.33)pg ml vs.(49.77±6.15)pg ml],差异有统计学意义(t=1.99、1.99、2.20、2.27,P<0.05)。AHI与IL-33、sST2、TNF-α、ET-1呈高度正相关(r=0.79、0.84、0.86、0.80,P<0.05)。所有病例均未出现明显皮肤压伤、腹胀、气胸等不良反应。结论BIPAP与CPAP治疗老年OS患者疗效确切,安全性好,且能降低炎症因子,BIPAP效果更为显著,采用BIPAP呼吸机治疗可能是一个更好的选择。

白庄煤矿质量标准化建设创新与实践

安全质量标准化是煤矿安全生产的基础工程、形象工程和惠民工程,是打造本质安全型矿井的一项重要举措。2010年度安全标准化建设工作的扎实开展,推动了白庄煤矿安全稳定发展,杜绝了重伤和二级以上非伤亡以上事故,"三违"人数明显下降实现了安全生产"零"目标。

Virological response to adefovir monotherapy and the risk of adefovir resistance

AIM:To evaluate virological response to adefovir(ADV) monotherapy and emergence of ADV-resistant mutations in lamivudine(LAM)-resistant chronic hepatitis B patients.METHODS:Seventy-seven patients with documented LAM resistance who were treated with 10 mg/d ADV for>96 wk were analyzed for ADV resistance.RESULTS:At week 48 and 96,eight(10%)and 14(18%)of 77 LAM-resistant patients developed the ADV-resistant strain(rtA181V/T and/or rtN236T mutations),respectively.Hepatitis B virus(HBV)DNA levels during therapy were significantly higher in patients who developed ADV resistance than in those who did not.Incidence of ADV resistance at week 96 was 11%,8%and 6%among patients with complete virological response(HBV DNA level<60 IU/mL);0%,5%and 19%among patients with partial virological response(HBV DNA level≥60 to 2000 IU/mL);and 32%,34% and 33%among patients with inadequate virological response(HBV DNA levels>2000 IU/mL)at week 12,week 24 and week 48,respectively.HBV DNA levels >2000 IU/mL at week 24 showed best performance characteristics in predicting ADV resistance.CONCLUSION:Development of ADV resistance mutations was associated with HBV DNA levels,which could identify patients with LAM resistance who are likely to respond to ADV monotherapy.

Effect of siRNAs on HSV-1 Plaque Formation and Relative Expression Levels of RR mRNA

RNA interference (RNAi) is a process by which introduced small interfering RNA (siRNA) can cause the specific degradation of mRNA with identical sequences. The human herpes simplex virus type 1 (HSV-1) RR is composed of two distinct homodimeric subunits encoded by UL39 and UL40,respectively. In this study,we applied siRNAs targeting the UL39 and UL40 genes of HSV-1. We showed that synthetic siRNA silenced effectively and specifically UL39 and UL40 mRNA expression and inhibited HSV-1 replication. Our work offers new possibilities for RNAi as a genetic tool for inhibition of HSV-1 replication.

Transport phenomena in meniscus region of horizontal single belt casting

The horizontal single belt casting(HSBC)incorporating a single-impingement feeding system was simulated with an improved numerical model.Physical experiments were carried out on the pilot-scale caster for validation.The results show that the meniscus turbulence neither comes from the tundish region,nor from the impingement between the melt and the moving belt.It is the moving belt that gives rise to this high turbulence region,and this region can stir the melt near the meniscus.The feeding system studied and the moving belt give rise to a buffer region,which can optimize casting parameter variations,especially melt depth changes in the tundish.The temperature change rate of the bottom surface of the strip is around 4 times faster than that of the upper surface.

Expression and clinical significance of MN1 and PTEN gene in patients with acute myeloid leukemia

Objective:The aim of our study was to explore the correlations between both the genes,evolution and prognosis of the disease by detecting the expression of MN1(meningioma 1) gene and PTEN(phosphatase and tensin homolog) gene in patients with acute myeloid leukemia(AML).Method:MN1 and PTEN mRNA were detected by reverse transcription-PCR in mononuclear cells of 38 patients with AML and 13 patients with normal bone marrow.Results:Positive rates of MN1 and PTEN genes were 76.3% and 60.5% respectively in bone marrow mononuclear cells.The expression level of MN1 mRNA for the de novo group increased comparing with that for normal control group(P < 0.05),the expression level of PTEN mRNA for de novo group decreased obviously comparing with that for normal control group(P < 0.01),MN1 mRNA level decreased in remission group,while PTEN mRNA level increased comparing with that in de novo group(P < 0.05).MN1 mRNA level increased and PTEN mRNA decreased in relapsed group comparing with that in control group,and their difference was statistical significance(P < 0.05).The two genes' levels had negative correlations in acute myeloid leukemia(r =-0.314,P < 0.05).Conclusion:There is close correlations between expression of MN1 and PTEN genes and the prognosis and occurrence of acute myeloid leukemia,and their expression can be taken as significant indexes to access the de novo,relapse and prognosis of acute myeloid leukemia.

Effect of Dietary Lipid Levels on Fatty Acids Composition of Cultured Sparusaurata

The aim of this study was to determine the progressive evolution of fish muscle fatty acids composition feeding by different lipid levels of farmed Mediterranean gilthead sea bream （Sparusaurata）. During twenty one weeks, Sparusaurata were hand-feed two diets with protein and lipid ratios 47/20 （Diet A） and 45/22 （Diet B） respectively. At the end of the feeding period, lipid contents of muscle, as well as fatty acids profiles of different portions of the muscles were studied. Results indicated the effects of fatty acids profiles of diets throughout the liver and white muscle fillet （dorsal, middle and ventral）. These were more noticeable when Sparusaurata was fed on the diet Athat decreased the content of monounsaturated fatty acids （MUFA）, and polyunsaturated fatty acids （PUFA） in all the muscles during the period of feeding while the saturated fatty acids （SFA） content tended to increase and it was lower than ones in the muscles of Sparusaurata fed on diet B. The highest amount of PUFA and docosahexaenoic acid, （22：6n-3 DHA） were found among the different portions of ventral muscles. In addition, the progressive evolution of different parts of muscle＇s fatty acid profiles showed significant differences in contents of SFA, PUFA and especially the n-3 PUFA. However, the content of MUFA seems to be alike in different muscles and tended to decrease in dorsal and ventral muscle from Do to Df and inversely when the fish were fed on diet A.

Investment decision optimization for delayed product differentiation based on queuing theory

To balance inventory cost with diverse demand,an optimal investment decision on necessary process improvement for delayed product differentiation is studied. A two-stage flexible manufacturing system is modeled as a continuous time Markov chain. The first production stage manufactures semifinished products based on a make-to-stock policy. The second production stage customizes semi-finished products from the first production stage on a make-to-order policy. Various performance measures for this flexible manufacturing system are evaluated by using matrix geometric methods. An optimization model to determine the level of investment on process improvement that minimizes the manufacturer ’s total cost is established. The results show that,a higher investment level can reduce both the expected customer order fulfillment delay and the expected semi-finished products inventory. When the initial order penetration point is 0. 4,the manufacturer ’s total cost is reduced by 15. 89% through process investment. In addition, the optimal investment level increases with the increase in the unit time cost of customer order fulfillment delay,and decreases with the increase in the product value and the initial order penetration point.

Coal pillar mechanics of violent failure in U.S. Mines

This paper seeks to enhance the understanding that the horizontal stresses build up and release during coal pillar loading and unloading(post-failure) drawing upon three decades of observations, geomechanical monitoring and numerical modeling in bump-prone U.S. mines. The focus is on induced horizontal stress in mine pillars and surrounding strata as highly stressed pillars punch into the roof and floor, causing shear failure and buckling of strata; under stiff stratigraphic units of some western US mines, these events could be accompanied by violent failure of pillar cores. Pillar punching eventually results in tensile stresses at the base of the pillar, facilitating transition into the post-failure regime; this transition will be nonviolent if certain conditions are met, notably the presence of interbedded mudstones with low shear strength properties and proper mine designs for controlling seismicity and dynamic loads. The study clearly shows high confining stress build-up in coal pillars resulting in up to twice higher peak vertical stress and high strain energy accumulations in some western US mines in comparison with peak stresses predicted using common empirical pillar design methods. It is the unstable release of this strain energy that can cause significant damage resulting from pillar dilation and ground movements. These forces are much greater than the capacity of most common internal support systems, resulting in horizontal stressinduced roof falls locally, in mines under unremarkable far-field horizontal stress. Attention should be placed on pillar designs as increasing support density may prove to be ineffective. This mechanism is analyzed using field measurements and generic finite-difference stress analyses. The study confirms the higher load carrying capacity of confinement-controlled coal seams in comparison with structurally controlled coal seams. Such significant differences in confining stresses are not taken into account when estimating peak pillar strength using most common empirical techniques such as those proposed by Bieniawski and Salamon. While using lower pillar strength estimates may be considered conservative,it underestimates the actual capacity of pillars in accumulating much higher stress and strain energies,misleading the designer and inadvertently diminishing mine safety. The role of induced horizontal stress in mine pillars and surrounding strata is emphasized in coal pillar mechanics of violent failure. The triggering mechanism for the violent events is sudden loss of pillar confinement due to dynamic loading resulting from failure of overlying stiff and strong strata. Evidence of such mechanism is noted in the field by observed red-dust at the coal-rock interfaces at the location of coal bumps and irregular, periodic caving in room-and-pillar mines quantified through direct pressure measurements in the gob.