“A Bias Recognized Is a Bias Sterilized”: The Effects of a Bias in Forecast Evaluation

Are traditional tests of forecast evaluation well behaved when the competing (nested) model is biased? No, they are not. In this paper, we show analytically and via simulations that, under the null hypothesis of no encompassing, a bias in the nested model may severely distort the size properties of traditional out-of-sample tests in economic forecasting. Not surprisingly, these size distortions depend on the magnitude of the bias and the persistency of the additional predictors. We consider two different cases: (i) There is both in-sample and out-of-sample bias in the nested model. (ii) The bias is present exclusively out-of-sample. To address the former case, we propose a modified encompassing test (MENC-NEW) robust to a bias in the null model. Akin to the ENC-NEW statistic, the asymptotic distribution of our test is a functional of stochastic integrals of quadratic Brownian motions. While this distribution is not pivotal, we can easily estimate the nuisance parameters. To address the second case, we derive the new asymptotic distribution of the ENC-NEW, showing that critical values may differ remarkably. Our Monte Carlo simulations reveal that the MENC-NEW (and the ENC-NEW with adjusted critical values) is reasonably well-sized even when the ENC-NEW (with standard critical values) exhibits rejections rates three times higher than the nominal size.

Direct Actuation of Large Sized Valves by a Hydraulically Relieved Electromechanical Actuation System

Extensive actuation forces and strokes are required for the actuation of large sized valves normally implemented in high power hydraulic systems. A hydraulically piloted operation is, for now, the most suitable solution and state of the art. However, there are some applications where electromechanical valve actuation systems are at advantage against common pilot operation systems. In this contribution it is analyzed in which cases the application of electro-mechanical actuators can be of advantage and why displacement-controlled systems may be one of these applications. A novel electromechanical valve actuation system for large sized 4/3-way directional control valves for the use in displacement-controlled systems is presented. This new actuation system is characterized by a hydraulic relief of the centering springs. Therefore, the springs are only active in safety-critical conditions, such as a power outage. Since the actuator is not working against the spring force during every displacement, the necessary actuation force is reduced drastically. Thus, common electromechanical actuators can be used. In case of a power outage, the spring relief is deactivated causing the stored energy to center the spool in its neutral position. The performance of the novel actuation system is examined through measurements conducted on a manufactured demonstrator for valves of nominal size 25 with a flow rate of up to 600 l/min.

Design and Application of Spiral Wound Gasket Sealing for Big Opening Flange for High Temperature and Pressure Vessel

Metallic spiral-wound gasket sealing are generally applicable for the service conditions, which are subject to the periodic temperature and pressure changes, shocks or vibrations. The nominal size of the largest spiral wound gasket of flanges is according to the provisions of HG/T 20631; those more than this specification are in the scope of non-standard parts, which require customization and manufacturing. This paper aims for introducing the successful experience of the first application of customized for non-standard spiral-wound gasket sealing of the large opening flange used for pressure vessel which bears high temperature and high pressure. The paper demonstrated the basic principle and critical points for the design and application of customized non-standard spiral-wound gasket sealing for the large opening flange and provided the valuable reference of actual application experience for the design and manufacturing of similar components. This paper presents the experiences summary in the study field and provides valuable reference of actual application experience for the design and manufacturing of similar components.

“Virtual stent” – clinical evaluation and user experience of on-the-fly stent simulation in treatment of cerebral aneurysms

Background Predicting final stent position can be challenging when treating cerebral aneurysms. Third-Party software proved helpful in selecting proper stents in treatment planning. Recent angiographic systems provide basic stent simulation capabilities integrated in the post-processing software to simulate stent position. Goal of this analysis was to evaluate the simulation process and correlation with definite stent position. Materials and Methods Thirty-three datasets with fusiform (n = 10) and saccular (n = 23) aneurysms, treated with stent or flow-diverter, were processed. A “virtual stent” of the same (nominal) size was simulated and its position was compared to the treatment result. Simulated length was rated in five grades (too short, shorter, equal, longer, too long), with regard to side-branches, anchoring zone etc. Simulation quality (centerline recognition/adherence to vessel margins) was rated in three grades (no, minor or major corrections required). Results Simulation was successful in 32/33 cases (97%), with one abortive attempt (3%). In 27/33 simulations (82%), there was no need for centerline refinement. Minor corrections were necessary in four and major corrections in two cases. Simulated nominal length was rated “equal” in 14/33 (42%) cases and “shorter” or “longer” – but within acceptable range – in each 9/33 (27%) cases. Conclusion Basic stent simulation tools available with genuine angiographic workplace software can provide good simulation capabilities without need for third-party equipment. They can facilitate treatment planning and help to avoid shortage of devices. Yet, lack of calculation of foreshortening in large vessel diameters leaves the user to rely on their experience to account for device-specific properties.

Discongruence Index: predictor of prosthesis size loss after transcatheter aortic valve replacement

Introduction Prosthesis under-expansion has been associated with higher rates of complications and worse long term outcome after transcatheter aortic valve replacement (TAVR). The objective of the current study was to assess the value of a new “Discongruence index”, to predict the percentage of prosthesis size loss (compared to its nominal size). The “discongruence index” is obtained from the relation between transcatheter valve size and the patient body surface area. Methods A total of 247 consecutive patients with severe aortic stenosis that underwent TAVR with balloon expandable Edwards-Sapiens prosthesis or CoreValve Revalving system at our institution were included. The “Discongruence index” was calculated pre-procedurally as the ratio: selected transcatheter valve size (mm) / body surface area (cm2). Two-dimensional transesophageal echocardiography images were studied in the 120–135° plane after the prosthesis deployment, and the maximum anteroposterior diameter was measured (in millimeters). From this measurement was obtained the percentage of prosthesis size loss (compared to the prosthesis nominal size). Results Mean age was 82±6 years and 102 patients (41.3%) were men. Mean aortic valvular area before TAVR was 0,87±3,8 cm2, (indexed 0,36±0,1 cm2) and the mean aortic gradient 49,1±16,9 mmHg. Mean prosthesis maximum deployment was 18,9±2,7 mm; absolute loss of prosthesis size compared to nominal 6,5±2,8 mm and the percentage loss of prosthesis size 25.1±9,5%. The “Discongruence index” was predictor of the percentage of prosthesis size loss (y = 5,7650 + 1,3010x, p<0,001), see figure. Conclusions The “Discongruence index” is a useful tool to predict the percentage of prosthesis size loss after TAVR. This new index should be taken into consideration in the selection of transcatheter valve sizes to avoid prosthesis under-expansion. FUNDunding Acknowledgement Type of funding sources: None. Figure 1

EVALUATION OF THE EFFECT OF VARIOUS SURFICIAL POLLUTANTS AND ENVIRONMENTAL CONDITION ON SURFACE FRICTION PERFORMANCE OF ROAD PAVEMENT

Skip resistance of asphalt is an important parameter that can influence the safety of drivers on roads. Although there is a linear relationship between slipping on road surfaces and accidents, the impacts of pollutants for decreasing friction of roads is clear to researchers. Moisture and temperature influence friction and safety. In this research in SMA samples, three different gradations with the maximum nominal sizes of 19, 12.5 and 9.5, based on international standards were used. For polluting the surface, five materials that are found on roads were used, including fine-grained soil, sand, oil, soot and rubber powder. To measure the skip resistance, the British pendulum tester was used and for analysing macro-texture, the sand patch method was used. The results of this research showed that by increasing the maximum nominal size of aggregates, the depth of macro-texture in surfaces are grown and this is due to the decrease of fine aggregates in larger gradations. Because of the higher flexibility of pure bitumen, the applied compression pressure on rigid aggregates can cause indentations in the substrate and result in declining the roughness height of aggregates in the mixed surface. This leads to declining the hysteresis part of friction by increasing temperature.

Pilot Fracture Tests of Special Fine-Grained Composites

Mechanical fracture parameters were obtained for special fine-grained cement-based composites from three-point bending tests. A total of four sets of composite specimens were tested. All of the sets of composites were based on a general recipe and differ in the amount of high-strength aggregate and/or dispersed steel fibres present. Standardized prism specimens with a nominal size of 40 × 40 × 160 mm were used for the fracture tests after 131 days of curing. An initial notch was cut in the centre of the prisms with a depth approximately equal to one third of the specimen’s height. Three specimens from each set of composites were tested in the three-point bending fracture test configuration. Load versus midspan deflection diagrams were recorded. Experimentally obtained load vs displacement diagrams were corrected and analysed using the Effective Crack Model, the Work-of-Fracture method and an independent identification technique using numerical modelling. The most important mechanical fracture parameters, such as static modulus of elasticity, effective fracture toughness, specific fracture energy and effective tensile strength, were determined. Compressive and splitting tensile strength values were obtained from the halves of the specimens left over after the bending tests.

Removal of Ampicillin by Heterogeneous Photocatalysis: Combined Experimental and DFT Study

A long-term exposition of antibiotics represents a serious problem for the environment, especially for human health. Heterogeneous photocatalysis opens a green way for their removal. Here, we correlated the structural-textural properties of TiO2 photocatalysts with their photocatalytic performance in ampicillin abatement. The tested nanoparticles included anatase and rutile and their defined mixtures. The nominal size range varied from 5 to 800 nm, Aeroxide P25 serving as an industrial benchmark reference. The degradation mechanism of photocatalytic ampicillin abatement was studied by employing both experimental (UPLC/MS/MS, hydroxyl radical scavenger) and theoretical (quantum calculations) approaches. Photocatalytic activity increased with the increasing particle size, generally, anatase being more active than rutile. Interestingly, in the dark, the ampicillin concentration decreased as well, especially in the presence of very small nanoparticles. Even if the photolysis of ampicillin was negligible, a very high degree of mineralization of antibiotic was achieved photocatalytically using the smallest nanoparticles of both allotropes and their mixtures. Furthermore, for anatase samples, the reaction rate constant increases with increasing crystallite size, while the degree of mineralization decreases. Importantly, the suggested degradation pathway mechanism determined by DFT modeling was in very good agreement with experimentally detected reaction products.

Comparative analysis of API standard drilling pipes and those of with double shoulder tool joints

The paper presents the data on the types, design peculiarities and requirements for the drilling pipes used in construction, overhaul repair and sidetracking. The comparative analysis of the pipes made with single shoulder tool joint according to API standard, as well as high torque and high efficient double shoulder tool joints from the world leading producers Pipe-Metallurgy Company “TMK”, National Oilwell Varco (NOV), HILONG Group of Companies is provided. Comparative analysis of the drilling pipes, as well as the double shoulder tool joint is presented. The exchangeability and non-exchangeability of drilling pipes with single shoulder tool joint produced in accordance with API standard with those of double shoulder tool joints indicating their structural features are marked as well. The comparison of stability coefficients of torques of drilling pipes in regard to the pipe body characterizing important operation parameters of nominal size of drilling pipe with double shoulder tool joint used in the overhaul repairs and sidetracking are provided.

Differential Action of Silver Nanoparticles on ABCB1 (MDR1) and ABCC1 (MRP1) Activity in Mammalian Cell Lines

Silver nanoparticles (AgNPs), due to their unique properties have been receiving immense attention in recent years. In addition to their antibacterial and antifungal activities, AgNPs also cause apoptosis, mitochondria disfunction, nucleic acid damage and show potent anticancer properties in both multidrug resistance (MDR) and sensitive tumors. The MDR phenomenon, caused by the presence of ATP-binding cassette (ABC) proteins, is responsible for the failure of chemotherapy. Thus, investigating the influence of widely used AgNPs on ABC transporters is crucial. In the present study, we have examined the cytotoxicity of silver nanoparticles of a nominal size of 20 nm (Ag20) on the cell lines of different tissue origins. In addition, we have checked the ATP-binding cassette transporters’ activity and expression under AgNP exposure. The results indicate that Ag20 shows a toxic effect on tested cells, as well as modulating the expression and transport activity of ABC proteins.