Optimizing the utilization of scad fish (Decapterus spp.) resource in northern coast of Aceh

For ten years, the Scad fish production in the Northern Coast of Aceh has been increasing rapidly at 172.5%. This condition describes that the Scad fish resource exploitation is implemented under improper management that could encounter an overfishing case. This study aimed to analyze the Scad fish resource utilization level and recommend a management strategy to achieve an optimized Scad fish resource utilization in the Northern Coast of Aceh. This study was performed in the Ocean Fishing Port, Kutaraja, Banda Aceh. Bioeconomic analysis results showed that catching product and effort in MSY condition at 2,838.59 tons and 2,808 trips by economic rent was Rp23,902 million per year. In MEY condition, catching product at 2,748.01 ton with catching effort at 2,311 and economic rent was Rp25,056 million per year. The open-access condition of Scad fish resource with total catching effort at 5,386 trips and economic rent value obtained was Rp 0. Results demonstrated that the Scad fish resource utilization status in the Northern Coast of Aceh encounters biological and economical overfishing. The Scad fish resource management strategy for achieving MSY and MEY condition through input control and output control by establishing the total allowed catching product and catching quota.

Method of enthalpy calibration for differential scanning calorimeters

The article describes a new method for enthalpy calibration of differential scanning calorimeters. The method allows you to remove the limitation on the temperature range in which this metrological procedure can be carried out. The proposed method does not require the use of standard samples of heats of fusion, therefore, it is not limited by the thermophysical properties of the certified substances. The developed method solves the problem of increasing the accuracy of measurements of specific enthalpy and heats of phase transitions of various substances for all types of differential scanning calorimeters. The effectiveness of the method in solving this problem is confirmed and illustrated by the authors by comparing the results of measuring the heats of fusion of a number of metals. The results obtained on differential scanning calorimeters calibrated by the new method and on the same instruments, but calibrated in accordance with the generally accepted standardized method of the International Union of Theoretical and Applied Chemistry, were compared. The authors experimentally revealed the advantages of the new method in terms of saving time and money required for calibration. The article will be of interest to those specialists who use differential scanning calorimeters in the development of new materials, control of technological processes, production, input and output control, as well as to those specialists who develop methods for research and measurement of various materials on differential scanning calorimeters.

Virtual Actuator Design for Uncertain Metzler Systems

The paper presents the design conditions adequate in design of virtual actuators and utilizable by nominal static output control structures in fault-tolerant control for strictly Metzler systems. The positive stabilization with H∞ norm performance is also addressed for virtual actuator design for strictly Metzler systems with interval uncertainty matrix representations of single actuator faults. Taking into account disturbance conditions and changes of values of variables after the virtual actuator activation, the design conditions are outlined in the terms of linear matrix inequalities. The approach provides a way to obtain acceptable dynamics of the closed loop system after virtual actuator activation.

Between automation and gamification: forms of labour control on crowdwork platforms

Algorithmic management is a core concept to analyse labour control on online labour platforms. It runs the risk, however, of oversimplifying the existing variety and complexity of control forms. In order to provide a basis for further research, this article develops a typology of labour control forms within crowdwork and discusses how they influence perceptions of working conditions. It identifies the two most relevant forms of labour control in crowdwork: direct control mainly takes the form of automated output control, while indirect control aiming at creating motivation and commitment is mainly exerted through ranking and reputation systems (gamification). The article shows that these forms of control and their combination are linked with very different ways of how platform workers perceive working conditions on platforms. In addition, the analysis shows significant differences regarding the perception of working conditions between those who work on platforms in addition to a regular employment as opposed to those who are self-employed and rely more strongly, if not fully, on their income from platform work. The analysis is based on qualitative and quantitative research on crowdwork platforms. In particular, it builds on an online survey conducted with 1,131 crowdworkers active on different types of platforms.