Layer Adhesion Test of Additively Manufactured Pins: A Shear Test

Additive Manufacturing (AM) became a popular engineering solution not only for Rapid Prototyping (RP) as a part of product development but as an effective solution for producing complex geometries as fully functional components. Even the modern engineering tools, such as the different simulation software, have a shape optimization solution especially for parts created by AM. To extend the application of these methods in this work, the failure properties of the 3D-printed parts have been investigated via shear test measurements. The layer adhesion can be calculated based on the results, which can be used later for further numerical modeling. In conclusion, it can be stated that the layer formation and the structure of the infill have a great influence on the mechanical properties. The layers formed following the conventional zig-zag infill style show a random failure, and the layers created via extruded concentric circles show more predictable load resistance.

Figure-of-Merit for a Long-Term Survivorship of a Species Determined from the Short-Term Mortality Rate of Its Individual Organisms

The two analytical (“mathematical”) probabilistic predictive models considered in this analysis suggest that (1) the nonrandom time-derivative of the long-term mortality rate at a rather arbitrary initial moment of time for a particular type of species of interest can be viewed as a suitable physical or biological criterion, a sort of a figure of merit (FoM), of its long-term viability/survivorship and that (2) this derivative can be determined as the variance of the random mortality rate for the significantly shorter, of course, lifespan of the individual organisms that the type of species as a whole, addressed by the first model, is comprised of. This suggestion is obtained as a modification and extension of and as an “analogy” to a concept that the author developed earlier in application to microelectronics products. So, it is assumed in our approach that the long-term survivorship of a species comprised of numerous individual organisms is analogous to the long-term performance of an electronic product comprised of numerous mass-produced components. In the original research, it was shown that the time-derivative at the initial moment of time of the nonrandom infant mortality portion (IMP) of the bathtub curve (BTC) for an electronic product is, in effect, the variance of the random failure rate (RFR) of the mass-produced components that this product is comprised of, and it is assumed that such an analogy is applicable also to the long-term survivorship of a species comprised of numerous individual organisms. The larger this variance, the shorter is the expected long-term lifetime (survivorship) of the species as a whole. Future work should be focused, first of all, on the verification of the trustworthiness of our basic assumption for different species, including humans, and on the accumulation of statistical data for long-term survivorship of various species and their existing or future habitats, with consideration of the roles of gravity, temperature, level of radiation, attributes of the atmosphere, if any, etc., as well as on calculating lifespan variances for the organisms that the species of interest are comprised of.

Performance Analysis of Photovoltaic Systems Using (RAMD) Analysis

The primary aim of this present study is to examine how reliability, availability, maintainability, and dependability (RAMD) are used to describe the criticality of each sub-assembly in grid- connected photovoltaic systems. A transition diagram of all subsystems is produced for this analysis, and Chapman-Kolmogorov differential equations for each variable of each subsystem are constructed using the Markov birth-death process. Both random failure and repair time variables have an exponential distribution and are statistically independent. A sufficient repair facility is still available with the device. The numerical results for reliability, maintainability, dependability, and steady-state availability for various photovoltaic device components have been obtained. Other metrics, such as mean time to failure (MTTF), mean time to repair (MTTR), and dependability ratio, which aid in device performance prediction, have also been measured. According to numerical analysis. it is hypothesized that subsystem S4, i.e. the inverter, is the most critical and highly sensitive portion that requires special attention in order to improve the efficiency of the PV device plant. The findings of this research are very useful for photovoltaic system designers and maintenance engineers.

Analysis of the Frequency and Onset Time of Hyponatremia/Syndrome of Inappropriate Antidiuretic Hormone Induced by Antidepressants or Antipsychotics

Background Hyponatremia and syndrome of inappropriate antidiuretic hormone (SIADH) is a potentially fatal adverse effect of antidepressants (ADs) and antipsychotics (APs), although its frequency and onset time have not been well documented. Objective To analyze the frequency and onset time of AD- or AP-induced hyponatremia/SIADH. Methods We used plural data-mining techniques to search the US Food and Drug Administration Adverse Event Reporting System (FAERS) database for reports on hyponatremia/SIADH induced by psychotropic drugs from January 2004 to June 2020. For each item, we assessed the reporting odds ratio, 95% CI, median onset time, and Weibull distribution parameters. Results We identified 36 422 reports related to hyponatremia/SIADH. Signals were detected for all psychotropic drugs that we analyzed, except for clozapine. The median onset time of total AD-induced hyponatremia/SIADH was shorter than that of AP. For all ADs and APs except clozapine, hazards were considered to be the early failure type. In contrast, the hazard of clozapine was considered to be the random failure type. The limitations of this study included several reporting biases and the presence of confounding variables, particularly age. Conclusion and Relevance Most ADs and APs were found to be associated with a risk for hyponatremia/SIADH. In addition, sufficient attention should be paid to signs of hyponatremia/SIADH in the early phase when most ADs and APs are administered. These data are potentially useful for determining AD- or AP-induced hyponatremia/SIADH in the early stage and for preventing its further aggravation into a serious condition.

Regional Pole Placers of Power Systems Under Random Failures/Repair Markov Jumps

This paper deals with a discrete-time stochastic control model design for random failure prone and maintenance in a single machine infinite bus (SMIB) system. This model includes the practical values of failure/repair rate of transmission lines and transformers. The probability matrix is, therefore, calculated accordingly. The model considers two extreme modes of operations: the most reliable mode and the least reliable contingency case. This allows the control design which stochastically stabilizes the system under jump Markov disturbances. For adequate transient response, the proposed state feedback power system stabilizer (PSS) achieves a desired settling time and damping ratio by placing the closed-loop poles in a desired region. The control target should also be satisfied for load variations in either mode of operation. A sufficient condition is developed to achieve the control objectives via solving a set of linear matrix inequalities (LMI). Using simulation, the performance of the designed controller is tested for the system that prone to random failure/maintenance under various loading conditions. Simulation results reveal that the closed-loop poles reside within the desired region satisfying the required settling time and damping ratio under the aforementioned disturbances. The contributions of the paper are summarized as follows: (1) modeling of transition probability matrix under Markov Jumps using practical data, (2) designing a controller by compelling the closed poles into the desired region to achieve adequate dynamic performance under different load varying conditions.

Crash behavior modeling and analysis on two interdependent networks

In real-world systems, one random failure or targeted attack may lead to the cascading destruction within a system, and even create the systemic collapse among multiple correlated ones. With the help of network science, modeling the cascade failure on complex networks has become a challenging topic. In this paper, we put forward an improved cascading model on two interdependent networks to further explore the impact of the specific detachment logic on the system collapse, where the distinct condition to leave the system for a pair of nodes exists on the two-layered networks. Meanwhile, once the detachment logic is satisfied, two different criteria are adopted to determine whether this pair of nodes will leave the interdependent networks. Through extensive numerical simulations, we analyze the effects of detachment logic, network topology, departure criteria and nodal coupling relationship between layers in detail. It is found that in our detachment logic, both criteria will render the whole system to exhibit the phenomenon of pseudo-steady state and sudden collapse. In particular, two critical thresholds to characterize the evolution of system crashing emerge, which is different from previous findings under other detachment logic conditions on two-layered networks. Current results are conducive to further understanding the crashing behaviors of interdependent networks and designing the more robust networked systems in practice.