Comment on “Impacts of historical warming on marine fisheries production”

Free et al. (Reports, 1 March 2019, p. 979) linked sea surface temperature (SST) to surplus production and estimated a 4% decline in maximum sustainable yield (MSY) since 1930. Changes in MSY are expected when fitting production models to age-structured data, so attributing observed changes to SST is problematic. Analyses of recruitment (a metric of productivity in the same database) showed increases in global productivity.

Development of Large Diameter Heavy Wall Seamless Tee Fitting of WPHY-80 Grade for Low Temperature Pipeline Station Application

This paper describes the development of large diameter heavy wall seamless tee fitting of WPHY-80 grade for low temperature pipeline station application. Steel tees with thicker wall generally tend to have low fracture toughness either in pipe body or in weld joint and low weldability. Therefore, improvement of fracture toughness and weldability are particularly important with respect to development of higher strength and thicker wall seamless tee fittings. For the requirement of the China-Russia Eastern Gas Pipeline Project, WPHY-80 large diameter, seamless heavy wall reducing outlet tees were developed, with DN1400 × DN1200 and 57mm wall thickness. The billet steel production process was electroslag remelting (ESR), and the tee fitting production process used a forging and hot extrusion combination. Finally, quenching and tempering were carried out. In this paper, the mechanical properties and microstructure of WPHY-80 seamless tee were studied. The results of mechanical testing showed that the tensile yield strength of the tee body was more than 590 MPa and also provided excellent low temperature toughness (CVN > 200 J at −45°C), which met the requirements of the specification for fittings applied in the China-Russia Eastern Gas Pipeline Project. In addition, the results of welding procedure qualification showed that the welding performance of the WPHY-80 seamless tee was excellent.

Design and Realization of Remote Monitoring System for Automatic Forced Fitting Production Line

In this paper, Aim at the lower degree of automation in forced fitting procedure between spindle blade and whorl in spinning machine, an automatic forced fitting production line is successfully designed. Based on PLC, the fully-automation control system to the production line is developed through analyzing the overall design scheme of the production line and the rapport between each workstation. Moreover, the remote monitoring system of forced-fitting production line has been implemented with the combination of powerful WinCC software with PLC technology.

Extending production models to include process error in the population dynamics

Four methods for fitting production models, including three that account for the effects of error in the population dynamics equation (process error) and when indexing the population (observation error), are evaluated by means of Monte Carlo simulation. An estimator that represents the distributions of biomass explicitly and integrates over the unknown process errors numerically (the NISS estimator) performs best of the four estimators considered, never being the worst estimator and often being the best in terms of the medians of the absolute values of the relative errors. The total-error approach outperforms the observation-error estimator conventionally used to fit dynamic production models, and the performance of a Kalman filter based estimator is particularly poor. Although the NISS estimator is the best-performing estimator considered, its estimates of quantities of management interest are severely biased and highly imprecise for some of the scenarios considered.

The use of production-function analysis in forest management: eucalypts in Brazil, a case study

Production-function analysis is applied to data from a spacing research carried out for a hybrid of Eucalyptusurophylla S.T. Blake in Brazil. A logarithmic –reciprocal equation is chosen as the best fitting production function for the present data, and its elasticities of production, elasticity of scale, and elasticity of substitution are computed. Given the production function, the set of input quantities which maximize the present net worth of an infinite number of forest cycles for a range of discount rates is presented.