分形集的几何性质研究

本文讨论了分形集的稠密性、可切性、自相似性。

分形集的结构与性质

本文讨论了分形集的稠密性、可切性、自相似性、自仿射性以及多重分形等性质。

切除、手术台上灌洗和初期吻合处理在半结肠梗阻性病变

1930年Dudley介绍了切除、手术台上灌注和初期吻合技术.1984年以来,收住院的全部急性大肠梗阻病例均考虑采用这种一期术式.病便与手术技术:1984.1～1989.2急性大肠梗阻73例.年龄范围28～96岁,平均68岁.手术选长直切口,开腹探查病灶的分期和可切性.先完全游离横结肠、脾曲和降结肠,从主动脉起始部和胰腺下缘分别结扎、切断肠系膜下动、静脉.然后游离乙状结肠和直肠.在肿瘤外下方钳夹切断直肠。

Analyses and predictions of rock cuttabilities under different confining stresses and rock properties based on rock indentation tests by conical pick

The rock indentation tests by a conical pick were conducted to investigate the rock cuttability correlated to confining stress conditions and rock strength.Based on the test results,the regression analyses,support vector machine(SVM)and generalized regression neural network(GRNN)were used to find the relationship among rock cuttability,uniaxial confining stress applied to rock,uniaxial compressive strength(UCS)and tensile strength of rock material.It was found that the regression and SVM-based models can accurately reflect the variation law of rock cuttability,which presented decreases followed by increases with the increase in uniaxial confining stress and the negative correlation to UCS and tensile strength of rock material.Based on prediction models for revealing the optimal stress condition and determining the cutting parameters,the axial boom roadheader with many conical picks mounted was satisfactorily utilized to perform rock cutting in hard phosphate rock around pillar.

Influence of brittleness and confining stress on rock cuttability based on rock indentation tests

In order to understand the influence of brittleness and confining stress on rock cuttability,the indentation tests were carried out by a conical pick on the four types of rocks.Then,the experimental results were utilized to take regression analysis.The eight sets of normalized regression models were established for reflecting the relationships of peak indentation force(PIF)and specific energy(SE)with brittleness index and uniaxial confining stress.The regression analyses present that these regression models have good prediction performance.The regressive results indicate that brittleness indices and uniaxial confining stress conditions have non-linear effects on the rock cuttability that is determined by PIF and SE.Finally,the multilayer perceptual neural network was used to measure the importance weights of brittleness index and uniaxial confining stress upon the influence for rock cuttability.The results indicate that the uniaxial confining stress is more significant than brittleness index for influencing the rock cuttability.

Scratching and Turning Experiments on Machinability of Optical Glass SF6 in Diamond Cutting Process

To improve the machinability of optical glass and achieve optical parts with satisfied surface quality and dimensional accuracy, scratching experiments with increasing cutting depth were conducted on glass SF6 to evaluate the influence of cutting fluid properties on the machinability of glass. The sodium carbonate solution of 10.5% concentration was chosen as cutting fluid. Then the critical depths in scratching experiments with and without cutting fluid were examined. Based on this, turning experiments were carried out, and the surface quality of SF6 was assessed. Compared with the process of dry cutting, the main indexes of surface roughness decrease by over 70% totally. Experimental results indicated that the machinability of glass SF6 can be improved by using the sodium carbonate solution as cutting fluid.

The Conflict Analysis Between the Asset Impairment Loss and Accounting Information Quality Requirements

New accounting standards set that once any loss of asset impairment is recognized, here mainly refer to long-term assets, it shall not be switched back in the future accounting periods. In the author＇s opinion, this provision has some conflicts with the accounting information quality requirements which require reliability, relevance, comparability, and caution. This paper mainly analyzes the contradictions by comparing the provision with the requirements and putting forward relevant solutions. In the end, this paper has drawn the conclusion that the loss of the long-term asset impairment shall be allowed to switch back with certain conditions.

Management of stage Ⅳ rectal cancer: Palliative options

Approximately 30% of patients with rectal cancer present with metastatic disease. Many of these patients have symptoms of bleeding or obstruction. Several treatment options are available to deal with the various complications that may afflict these patients. Endorectal stenting, laser ablation, and operative resection are a few of the options available to the patient with a malignant large bowel obstruction. A thorough understanding of treatment options will ensure the patient is offered the most effective therapy with the least amount of associated morbidity. In this review, we describe various options for palliation of symptoms in patients with metastatic rectal cancer. Additionally, we briefly discuss treatment for asymptomatic patients with metastatic disease.

Reliability analysis of laminated composite under compression and shear loads

Carrying on a series of compression and shear tests by a large number of specimens, reliabilities of T300/QY8911 laminated composite were studied when dispersibility models were described. The results show that the stress is linearly dependent on the strain and the damage modes of specimens are brittle fracture for both kinds of tests. Dispersibility models of compression and shear strength are expressed as Re-N（415.39, 6 586.36） and Rs-ln（5.071 8, 0.155 3）, respectively. When normal and lognormal distributions were used to describe the dispersibility models of compression and shear strength, and the compression or shear load follows the normal distribution, the almost same failure probability can be obtained from different reliability analysis methods.

Low secondary compressibility and shear strength of Shanghai Clay

In order to investigate the compressibility, particularly the secondary compression behaviour, soil structure and undrained shear strength of Shanghai Clay, a series of one-dimensional consolidation tests （some up to 70 d） and undrained triaxial tests on high-quality intact and reconstituted soil specimens were carried out. Shanghai Clay is a lightly overconsolidated soil （OCR=1.2-1.3） with true cohesion or bonding. Due to the influence of soil structures, the secondary compression index Ca varies significantly with consolidation stress and the maximum value of C~ occurs in the vicinity of preconsolidation stress. Measured coefficients of secondary compression generally fall in the range of 0.2%-0.8% based on which Shanghai Clay can be classified as a soil with low to medium secondary compressibility. The effect of soil structures on the compressibility of Shanghai Clay is found to reduce with an increase in depth. Soil structure has an important influence on initial soil stiffness, but does not appear to affect undrained shear strength significantly. Undrained shear strengths of intact Shanghai Clay from compression tests are approximately 20% higher than those from extension tests.

A lexicalized second-order-HMM for ambiguity resolution in Chinese segmentation and POS tagging

Hidden Markov Model（HMM） is a main solution to ambiguities in Chinese segmentation anti POS （part-of-speech） tagging. While most previous works tot HMM-based Chinese segmentation anti POS tagging eonsult POS informatiou in contexts, they do not utilize lexieal information which is crucial for resoMng certain morphologieal ambiguity. This paper proposes a method which incorporates lexieal information and wider context information into HMM. Model induction anti related smoothing technique are presented in detail. Experiments indicate that this technique improves the segmentation and tagging accuracy by nearly 1%.

Effects of High CO_2 Pretreatment on the Quality of Fresh-Cut Potatoes

Effects of short-term high CO_2 pretreatment on quality of fresh-cut potatoes were studied. Potatoes were treated under 90% CO_2 for 18 h, peeled, cut, dipped in 1% ascorbic acid or distilled water for 3 min, packed in polyethylene bags and stored for 12 d at 4 ℃. Non-treated potatoes were used as the control. High CO2 pretreatments ensured maintenance of a high level of CO_2 in headspace of packages containing fresh-cut potatoes. Both the growth of total aerobic bacteria in initial stages of post-cut storage and browning index of the cut surface were lower in high CO_2 treated cut potato. Anti-browning effect of high CO_2 pretreatment was decreased when applied in combination with ascorbic acid. Soluble solids, pH, titratable acidity and flesh firmness of fresh-cut potatoes were not affected by high CO_2 treatment. Therefore, high CO_2 treatment before slicing could be effective method to maintain quality of flesh-cut potatoes.

How does the initial free volume distribution affect shear band formation in metallic glass?

Introducing heterogeneities into the structure is an effective way to enhance the plasticity in metallic glasses (MGs). As natural heterogeneity, the original randomly distributed free volume in MGs has been found to be in favor of plasticity. However, the exact correlation between the free volume distribution and mechanical response is still unclear. In this paper, we investigate the shear banding in MGs with different structural disorders, characterized by both the free volume concentration (FVC) and the free volume dispersion (FVD). It is found that, either high FVC or wide FVD leads to low activation stress of shear band; wide FVD promotes the multiplication of shear bands but high FVC restricts it. It reveals that the yield strength in MGs is dependent on the amount of free volume while the plasticity mainly relies on the distribution. An optimum combination of the two aspects probably helps to design a MG of both good plasticity and high strength.

A reversible acid-base fluorescent switch based on molecular cocrystal of 4-[2-4-quinolinyl)vinyl]phenol and tetrafluoroterephthalic acid

Photoactive cocrystal materials have received growing research interest in construction of photofunctional systems owing to the crucial roles in modifying the photo-related properties of molecular solids, based on the non-bonding interactions between self-assembly units. Herein, we report tunable luminescence and acid-base stimuli-responsive properties of a cocrystal assembled by 4-[2-(4-quinolinyl)vinyl]phenol (qv) and tetrafluoroterephthalic acid (a). The luminescent properties (such as wavelength, quantum yield and fluorescence lifetime) of qv.a changed obviously relative to the pristine qv, due to the proton transfer and the alternation of molecular arrangement within two-component crystalline material. The photoemission intensity of qv.a underwent from weak to strong upon HCl gas fuming, and the corresponding wavelength changed from 517 nm to 597 nm, which can be reversibly transferred after exposed in NH3. Such luminescent switching behavior may provide an effective way to develop new types of photoactive stimuli-responsive materials and optical sensors.

Simulation of non-Newtonian (Power-law) fluid flow past a row of square cylinders

The power-law fluid flow past a row of uniform placed square cylinders is investigated using the Lattice Boltzmann method (LBM).The flow is assumed to be two-dimensional and incompressible.The relaxation time is assumed to be shear-dependent and determined by using a variable parameter related to the local shear rate.The effects of both shear-thinning/shear-thickening property and the cylinder spacing on the confluence of the jets are mainly concerned.The bifurcation diagrams of the flow are obtained,which include confluences of double and quadruple jets.The results show that both the first and second pitchfork bifurcations are advanced due to the effect of the shear-thinning property,and postponed due to the shear-thickening property.

On Regularity of Incompressible Fluid with Shear Dependent Viscosity

The authors consider a non-Newtonian fluid governed by equations with p-structure in a cubic domain.A fluid is said to be shear thinning(or pseudo-plastic) if 1 < p < 2,and shear thickening(or dilatant) if p > 2.The case p > 2 is considered in this paper.To improve the regularity results obtained by Crispo,it is shown that the secondorder derivatives of the velocity and the first-order derivative of the pressure belong to suitable spaces,by appealing to anisotropic Sobolev embeddings.