Working with ARMs: Complexity Results on Atomic Representations of Herbrand Models

An atomic representation of a Herbrand model (ARM) is a finite set of (not necessarily ground) atoms over a given Herbrand universe. Each ARM represents a possibly infinite Herbrand interpretation. This concept has emerged independently in different branches of computer science as a natural and useful generalization of the concept of finite Herbrand interpretation. It was shown that several recursively decidable problems on finite Herbrand models (or interpretations) remain decidable on ARMs.The following problems are essential when working with ARMs: Deciding the equivalence of two ARMs, deciding subsumption between ARMs, and evaluating clauses over ARMs. These problems were shown to be decidable, but their computational complexity has remained obscure so far. The previously published decision algorithms require exponential space. In this paper, we prove that all mentioned problems are coNP-complete.     

Synergistic effect of benzoate and benzotriazole on passivation of mild steel

The electrochemical behaviour of mild steel was investigated in near neutral air saturated solutions containing benzoate (Bzo) and benzotriazole (BTA), separately or mixed. In the benzoate/BTA mixtures the open circuit passivation was found to be much better than in pure benzoate electrolytes. Electrochemical impedance spectroscopy (EIS) measurements resulted in characteristic Bode plots due to the synergistic effect of both inhibitors in the presence of oxygen. Open circuit potential (OCP) measurements vs. time supported the observed behaviour. The inhibition effect can be attributed to the blocking of surface sites for anodic dissolution by benzoate and a subsequent strong adsorption of benzotriazole on the natural oxide layer.     

Investigation of diamond deposition uniformity and quality for freestanding film and substrate applications

In this paper, we report on microwave CVD deposition of high quality polycrystalline diamond and on related post-processing steps to produce smooth, flat and uniformly thick films or diamond substrates. The deposition reactor is a 2.45 GHz microwave cavity applicator with the plasma confined inside a 12 cm diameter fused silica bell jar. The deposition substrates utilized are up to 75 mm diameter silicon wafers. The substrate holder is actively cooled with a water-cooled substrate holder to achieve a substrate surface temperature of 600–1150 C. The pressure utilized is 60–180 Torr and the microwave incident power is 2–4.5 kW. Important parameters for the deposition of thick films with uniform quality and thickness include substrate temperature uniformity as well as plasma discharge size and shape. As deposited thickness uniformities of ± 5% across 75 mm diameters are achieved with simultaneous growth rates of 1.9 μm/h. The addition of argon to the deposition gases improves film deposition uniformity without decreasing growth rate or film quality, over the range of parameters investigated. Post-processing includes laser cutting of the diamond to a desired shape, etching, lapping and polishing steps.     

Two‐Step Protein Labeling by Using Lipoic Acid Ligase with Norbornene Substrates and Subsequent Inverse‐Electron Demand Diels–Alder Reaction

Inverse‐electron‐demand Diels–Alder cycloaddition (DA_inv) between strained alkenes and tetrazines is a highly bio‐orthogonal reaction that has been applied in the specific labeling of biomolecules. In this work we present a two‐step labeling protocol for the site‐specific labeling of proteins based on attachment of a highly stable norbornene derivative to a specific peptide sequence by using a mutant of the enzyme lipoic acid ligase A (LplA^W37V), followed by the covalent attachment of tetrazine‐modified fluorophores to the norbornene moiety through the bio‐orthogonal DA_inv . We investigated 15 different norbornene derivatives for their selective enzymatic attachment to a 13‐residue lipoic acid acceptor peptide (LAP) by using a standardized HPLC protocol. Finally, we used this two‐step labeling strategy to label proteins in cell lysates in a site‐specific manner and performed cell‐surface labeling on living cells.     

A numerical model for fluid injection induced seismicity at Soultz-sous-Forêts

During fluid injection experiments at the geothermal site of Soultz-sous-Forêts (France), more than 114,000 induced seismic events with magnitudes between ?2.0 and +2.9 were detected by a local downhole monitoring network. Of these, 35,039 events are sufficiently constrained to be located. Hypocenters align along a sub-vertical, planar structure with the apparent width being dominated by data scattering indicating that seismic activity predominantly occurs along a (pre-existing) larger scale fault structure. For this scenario, we present a numerical model to simulate hydraulic overpressures and induced seismicity during hydraulic injection. The numerical model is based on the physical processes of fluid pressure and stress diffusion with triggering of the induced seismicity being controlled by Coulomb friction.Even in its simplest form of a fault zone without any structural heterogeneity, the numerical model reproduces typical observations at Soultz-sous-Forêts, such as number and magnitude of induced events, hypocenter locations (including the Kaiser effect), occurrence of post-injection seismicity, and the largest magnitude event occurring several days after shut-in.     

采煤机截割状态与煤岩识别的关联载荷特征模型

针对采煤工作面煤层的厚度变化、含夹矸和包裹体的不确定性,以及复杂煤岩占比和岩层位置辨识的差异,致使采煤机在截割过程中会产生无效调整截割高度的情况,影响其可靠性和智能化技术水平。截割煤岩载荷特征及其关联截割状态的模型可以预测、修正和决策采煤机截割行为,提升采煤机智能化程度。借鉴多信息实时修正记忆截割与煤层三维地质信息建模等方法,提出了采煤机自主调高-调速二元协同控制模式及截割状态关联特征模型,考虑煤岩赋存条件以及滚筒相对煤岩层的位置和工作参数,划分滚筒截割过程为顺转截割、逆转截割、向和逆自由面截割以及截割顶底板和夹矸等截割状态,分析截齿截割煤岩的过程与状态,构建了向和逆自由面截割状态特征量的数学模型和截割顶底板位置与占比的识别定量载荷关联特征模型,给出了截齿垂直、平行于层理方向截割力的累计占比计算方法,通过旋转截割实验验证截割煤岩载荷特征模型的准确性。根据截割顶、底板、夹矸岩层前后载荷变化导致的截割电机电流变化规律与调高液压缸两腔压力的关联性变化规律,结合截割状态的关联载荷特征模型,修正与预测截割状态和岩层位置,确定了修正采煤机调高调速行为协调控制的截割状态特征参量。研究表明:向自由面截割煤岩断裂位置大于逆自由面的,向自由面易于破碎煤岩,且截割载荷与比能耗均小;分别获取截齿截割顶底板载荷增量与方向角,载荷增量均与岩层厚度呈正相关性,但截割顶底板方向存在明显差异;随截割夹矸岩层厚度增加,截齿截割载荷增大,且截割载荷与夹矸位置呈抛物线关系;给出截齿垂直和平行层理截割力特征值占比的度量,反映截割顶板易于截割底板的特征;截齿向自由面截割煤岩理论和实验的截割阻力功特征值、断裂位置和断裂崩落线与截割点垂线夹角的平均误差分别为3.10%,3.37%和8.07%,验证了截割煤岩状态特征量数学模型的正确性。该研究通过给出融合载荷特征的截割状态修正与煤岩状态识别的理论基础描述,为进一步精准实现智能化采煤机调高-调速二元协调控制提供了借鉴。     

Zum einfluß des borat-anions auf die elektrochemischen eigenschaften des eisens in Wäßrigen Lösungen

Measurements of potential—time and current density—potential curves of iron were carried out in air-saturated and argon-flushed sodium borate solutions of different concentrations and pH to determine whether borate anions possibly influence the electrochemical behaviour of iron even in the absence of oxygen. The critical minimum pH necessary for passivating iron in air-saturated borate solutions has been established. Using these results and those taken from the literature we discuss the role of the borate anion in possibly stimulating the process of oxygen reduction and/or in influencing the process of metal oxydation, respectively. The latter influence, leading to a decrease of the critical current density, does not absolutely require the presence of oxygen. However, with the formation of hydrogen as the cathodic reaction it cannot give rise to the passive state of iron. The relation between the potential of the passive iron electrode in air-saturated borate solutions and the pH is explained by Fe(III)-borohydroxo-complexes possibly being formed on the solution side of the passive layer.     

Structural Stability of Solid Deuterium Films

The wetting behavior of quenched-condensed solid D₂ films has been investigated by means of light scattering. On the substrates used here (graphite and aluminum) molecular deuterium displays triple point wetting and hence dewets in the solid state, provided the temperature is high enough that thermally activated diffusion processes can take place. This manifests itself in a coarse-graining of the D₂ film. In order to avoid this process and to obtain complete wetting of solid D₂ we have modified the adsorbate-substrate interaction potential by preplating the substrates with thin inert layers of Ne, Ar, CH₄ or C₂H₆. The predicted change in the wetting properties was not observed, however, suggesting that the existing picture of triple point wetting of van der Waals systems is not complete. The implications of these results for a neutrino mass experiment where quenched-condensed molecular tritium films are used as a source are discussed.