Contact resistance based tactile sensor using covalently cross-linked graphene aerogels

A movable electrical contact between two materials is one of the most fundamental, simple, and common components in electronics that is used for binary control of a conducting path in...

Reducing underreporting of abortion in surveys: Results from two test applications of the list experiment method in Malawi and Senegal

Background Accurately measuring abortion incidence poses many challenges. The list experiment is a method designed to increase the reporting of sensitive or stigmatized behaviors in surveys, but has only recently been applied to the measurement of abortion. To further test the utility of the list experiment for measuring abortion incidence, we conducted list experiments in two countries, over two time periods. Materials and methods The list experiment is an indirect method of measuring sensitive experiences that protects respondent confidentiality by hiding individual responses to a binary sensitive item (i.e., abortion) by combining this response with answers to other non-sensitive binary control items. Respondents report the number of list items that apply to them, not which ones. We conducted a list experiment to measure cumulative lifetime incidence of abortion in Malawi, and separately to measure cumulative five-year incidence of abortion in Senegal, among cisgender women of reproductive age. Results Among 810 eligible respondents in Malawi, list experiment results estimated a cumulative lifetime incidence of abortion of 0.9% (95%CI: 0.0, 7.6). Among 1016 eligible respondents in Senegal, list experiment estimates indicated a cumulative five-year incidence of abortion of 2.8% (95%CI: 0.0, 10.4) which, while lower than anticipated, is seven times the proportion estimated from a direct question on abortion (0.4%). Conclusions Two test applications of the list experiment to measure abortion experiences in Malawi and Senegal likely underestimated abortion incidence. Future efforts should include context-specific formative qualitative research for the development and selection of list items, enumerator training, and method delivery to assess if and how these changes can improve method performance.

A modified sliding mode control of a nonlinear methane fermentation process

A continuous methane fermentation process for biogas production is considered. This biogas production process is described by a system of two nonlinear differential equations and one nonlinear algebraic equation. The paper purpose is to propose an approach for designing a modified sliding mode control (so-called binary control) of a nonlinear methane fermentation process. The control design is carried out with direct use of nonlinear model and on-line measurement for two variables only (the concentration of the organic pollutants and biogas production rate). The model of the sliding mode control is developed with respect to an auxiliary input variable in order to obtain the smooth signal of the dilution rate, which is need in the fermentation processes. The state variables, external disturbance, process output and control input are varied in the known intervals. The asymptotic output stabilization problem is solved. The good system robustness with the designed modified sliding mode control (the binary control) about various disturbances is proved through simulation investigations in MATLAB using Simulink.

Experimental Comparison of Two Integer Valued Iterative Learning Control Approaches at a Stator Cascade

Experimental and simulative investigations have shown that active flow control (AFC) is an effective method to influence flow conditions within a compressor. This can be used for different cases like mitigating flow separation or to ensure a uniform flow throughout a compressor stage. Control performance can be improved by making use of a cyclic character found in the rotor/stator interaction or found in new gas turbine setups exploiting cycling combustion. To this end, iterative learning control (ILC) is applied. To achieve a fast actuation, irrespective of the implemented control method, solenoid valves should be installed instead of proportional valves. Unfortunately, the binary character of these valves does not allow the application of conventional control methods, e.g., real-valued ILC. This contribution presents two options to handle the binary control domain in the context of an ILC. Both approaches are tested in a simulation study first to analyze the behavior. Then they are applied to a real test rig featuring a linear stator cascade.