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11.
12.
We study three types of self‐reducibility that are motivated by the theory of program verification. A set A is random‐self‐reducible if one can determine whether an input x is in A by making random queries to an A‐oracle. The distribution of each query may depend only on the length of x. A set B is self‐correctable over a distribution if one can convert a program that is correct on most of the probability mass of to a probabilistic program that is correct everywhere. A set C is coherent if one can determine whether an input x is in C by asking questions to an oracle for C–{x}.?We first show that adaptive coherence is more powerful than nonadaptive coherence, even if the nonadaptive querier is nonuniform.
Blum et al.(1993) showed that every random‐self‐reducible function is self‐correctable. It is unknown, however, whether self‐correctability
implies random‐self‐reducibility. We show, assuming a reasonable complexity‐theoretic hypothesis, that certain hard, sparse,
tally sets exist, and that there is a self‐correctable function which is not random‐self‐reducible. For easily samplable distributions,
however, we show that constructing a self‐correctable function that is not random‐self‐reducible is as hard as proving that
P is different from PP.
Received: 14 June, 1996 相似文献
13.
Fabien Paulot David Paynter Vaishali Naik Sergey Malyshev Raymond Menzel Larry W. Horowitz 《International Journal of Hydrogen Energy》2021,46(24):13446-13460
Hydrogen (H2) has been proposed as an alternative energy carrier to reduce the carbon footprint and associated radiative forcing of the current energy system. Here, we describe the representation of H2 in the GFDL-AM4.1 model including updated emission inventories and improved representation of H2 soil removal, the dominant sink of H2. The model best captures the overall distribution of surface H2, including regional contrasts between climate zones, when vd(H2) is modulated by soil moisture, temperature, and soil carbon content. We estimate that the soil removal of H2 increases with warming (2–4% per K), with large uncertainties stemming from different regional response of soil moisture and soil carbon. We estimate that H2 causes an indirect radiative forcing of 0.84 mW m?2/(Tg(H2)yr?1) or 0.13 mW m?2 ppbv?1, primarily due to increasing CH4 lifetime and stratospheric water vapor production. 相似文献
14.
S. Bindiya S. Basavanna Y. Arthoba Naik 《Journal of Materials Engineering and Performance》2012,21(9):1879-1884
Composite coatings were obtained by electrochemical codeposition of V2O5 nanoparticles with zinc, from an additive free acid sulfate bath. The corrosion behavior of electrodeposited Zn and Zn-V2O5 composite coatings was investigated in 3.5% NaCl solution using polarization and electrochemical impedance spectroscopy (EIS). The decrease in I corr values and an increase in R ct values show the higher corrosion resistant nature of Zn-V2O5 coatings. The observed textural modifications of composite coatings are associated with the specific structural modification of Zn crystallites provoked by the adsorption-desorption phenomena occurring on the metal surface, induced by the presence of V2O5 nanoparticles. It has been observed that the presence of V2O5 nanoparticles favors the [1 0 2] and [1 1 2] texture of zinc matrix. Moreover, the codeposition of V2O5 nanoparticles with zinc was found to be favored at pH 3.5 and applied current density 4?A?dm?2. A considerable grain refinement of the deposit occurred due to incorporation of V2O5 nanoparticles and hence improved the preferred orientation of the zinc crystallites. 相似文献
15.
Physico‐mechanical properties of nano‐polystyrene‐decorated graphene oxide–epoxy composites 下载免费PDF全文
Prashant S Khobragade Dharmesh P Hansora Jitendra B Naik James Njuguna Satyendra Mishra 《Polymer International》2017,66(10):1402-1409
Nano‐polystyrene (nPS)‐decorated graphene oxide (GO) hybrid nanostructures were successfully synthesized using stepwise microemulsion polymerization, and characterized using Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), field‐emission scanning electron microscopy and transmission electron microscopy. XRD and FTIR spectra revealed the existence of a strong interaction between nPS and GO, which implied that the polymer chains were successfully grafted onto the surface of the GO. The nPS‐decorated GO hybrid nanostructures were compounded with epoxy using a hand lay‐up technique, and the effect of the nPS‐decorated GO on the mechanical, thermal and surface morphological properties of the epoxy matrix was investigated using a universal tensile machine, Izod impact tester, thermogravimetric analysis and contact angle measurements with a goniometer. It was observed that in the epoxy matrix, GO improved the compatibility. © 2017 Society of Chemical Industry 相似文献
16.
Shear Plugging and Frictional Behaviour of Composites and Fabrics Under Quasi‐static Loading 下载免费PDF全文
Experimental studies are presented on the shear plugging and frictional behaviour of composites and fabrics under quasi‐static loading. The primary focus is on the effect of specimen thickness on quasi‐static shear plugging behaviour. In the present study, quasi‐static shear plugging and through‐the‐thickness frictional tests are carried out on three types of materials. The materials investigated are 2D plain weave E‐glass/epoxy, 2D plain weave T300 carbon/epoxy and 2D plain weave E‐glass fabric. Typical results on shear plugging strength and frictional behaviour are presented. Effect of specimen thickness on quasi‐static shear plugging behaviour is also investigated. 相似文献
17.
Jayahari Lade Balu Naik Banoth Amit Kumar Gupta Swadesh Kumar Singh 《钢铁研究学报(英文版)》2014,21(12):1147-1151
Austenitic stainless steel 304 was deep drawn with different blank diameters under warm conditions using 20 t hydraulic press. A number of deep drawing experiments both at room temperature and at 150 ℃ were conducted to study the metallography. Also, tensile test experiments were conducted on a universal testing machine up to 700 ℃ and the broken specimens were used to study the fractography of the material using scanning electron microscopy in various regions. The microstructure changes were observed at limiting draw ratio (LDR) when the cup is drawn at different temperatures. In austenitic stainless steel, martensite formation takes place that is not only affected by temperature, hut also influenced by the rate at which the material is deformed. In austenitic stainless steel 304, dynamic strain regime appears above 300 ℃ and it decreases the formability of material due to brittle fracture as studied in its fractography. From the metallographic studies, the maximum LDR of the material is observed at 150 ℃ before dynamic strain regime. It is also observed that at 150 ℃, grains are coarse in the drawn cups at LDR. 相似文献
18.
The Change of X‐ray Diffraction Peak Width During in situ Conventional Sintering of Nanoscale Powders 下载免费PDF全文
Jean‐Marie Lebrun Shikhar K. Jha Kiran S. Naik Kevin C. Seymour Waltraud M. Kriven Rishi Raj 《Journal of the American Ceramic Society》2016,99(3):765-768
Diffraction peaks of nanoscale particles of 3 mol% yttria‐stabilized zirconia become sharper as the powder sinters. The reduction in the peak width is correlated with the increase in density. The sharpening of the peak agrees reasonably well with the remaining free surface area as the sample sinters. Therefore, high curvature of the free surface of the pores is assumed to lead to peak broadening (the grain boundaries that grow at the expense of the free surfaces of the pores do not have this curvature). The change in the grain size during sintering does not make a significant contribution to peak width. 相似文献
19.
An emulsion of pioglitazone hydrochloride (drug) was prepared by mixing drug:polymer (gelatin) in different ratios of 1:0.5, 1:1, and 1:1.5 (wt/wt), respectively. These emulsions were used for the preparation of tablets of different composition. Tablet hardness increased with a decrease in concentration of polymer, while the percentage friability increased with an increase in polymer concentration in the tablet. The encapsulated tablet showed better sustained release than conventional tablets. The effect of concentration of polymer on dissolution rates of these tablets was studied using the Hixson-Crowell cube root law equation. The data obtained prove that the formulations are useful for a sustained release of pioglitazone hydrochloride, since the percentage released after 24 h was nearly 76%. The release of pioglitazone hydrochloride was influenced by the presence of polymer and different compositions of lactose. The tablet containing an emulsion of ratio 1:0.5 showed an excellent result of rate constant, better than conventional and other compositions. 相似文献
20.
Liquid–liquid–liquid phase transfer catalysis (L–L–L PTC) offers orders of magnitude intensification of rates of reaction and better selectivities than the biphasic PTC. The catalyst-rich middle phase is the main reaction phase. The etherification or alkoxylation of p-chloronitrobenzene (PCNB) was conducted by using alkanol and alkali instead of the metal alkoxide. A kinetic model is presented and validated. 相似文献