Ronald Jones's duality analysis as a foundation for applied general‐equilibrium modeling

Ronald Jones made seminal contributions to general‐equilibrium theory, moving away from an emphasis on the existence of equilibrium to algebraic formulations which enabled us to characterize key relationships between parameters and variables, such as that between tariffs and domestic factor prices and welfare. But the analysis remained limited in value for policy evaluation: the analysis was local, it provided only qualitative results, it was limited to very small models, and strictly interior solutions had to be assumed. The contribution of this paper is largely pedagogic and methodological. I show how the tools and approach pioneered by Jones can be generalized via the use of duality, complementarity and the Karush–Kuhn–Tucker theorem into a global, quantitative analysis of large changes in high‐dimensional models which also allows for regime changes and corner solutions. I then show how the resulting nonlinear complementarity problem directly translates into a numerical model using the General Algebraic Modeling System (GAMS).     

Optimal investment with vintage capital: Equilibrium distributions

The paper concerns the study of equilibrium points, or steady states, of economic systems arising in modeling optimal investment with vintage capital, namely, systems where all key variables (capitals, investments, prices) are indexed not only by time but also by age. Capital accumulation is hence described as a partial differential equation (briefly, PDE), and equilibrium points are in fact equilibrium distributions in the variable of ages. A general method is developed to compute and study equilibrium points of a wide range of infinite dimensional, infinite horizon, optimal control problems. We apply the method to optimal investment with vintage capital, for a variety of data, deriving existence and uniqueness of equilibrium distribution, as well as analytic formulas for optimal controls and trajectories in the long run. The examples suggest that the same method can be applied to other economic problems displaying heterogeneity. This shows how effective the theoretical machinery of optimal control in infinite dimension is in computing explicitly equilibrium distributions. To this extent, the results of this work constitute a first crucial step towards a thorough understanding of the behavior of optimal paths in the long run.     

A Historical Review of Postponement Research

This historical review traces the development of postponement research starting in the fifties. The focus is on seven related themes: connecting form and time postponement, conceptual extensions to postponement, decoupling points, design for postponement, customization and mass customization, factors favoring postponement implementation, and postponement in global settings. Within these themes, the review includes concepts such as postponement costs, decoupling points, part commonality, and the impact of demand correlations on the benefits of postponement. The review suggests that substantial progress has been made in postponement research.     

Macroeconomic adjustment with managed exchange rates and capital controls: Some lessons from China

This paper examines the performance of capital controls and exchange-rate management when the economy finds itself in dark corners. These are times when the real sector experiences a sequence of prolonged negative shocks from world demand, while the central bank faces low world interest rates on its foreign-exchange reserve holdings. We examine two regimes, one of a fixed exchange rate with strong capital controls and another with a more open capital account with a managed exchange rate. We show how this model replicates recent experiences of China as it moved from a relatively fixed exchange rate regime with strong capital controls to a more flexible exchange rate regime with a more open capital account. Our results show that capital-account liberalization should be accompanied by domestic price liberalization to avoid large losses in foreign exchange reserve and jumps in unemployment during dark corners in the more open regime.     

浅谈泵送产品的公告试验检测

论文针对泵送产品公告试验检测的现状,详述了公告试验检测方案中的关键控制点,并就目前检测过程中存在的问题提出了建议。     

Effectiveness of harvest strategies in achieving multiple management objectives in a multispecies fishery

Fisheries management is characterised by multiple objectives, some of which may be complementary, while others may require trade‐offs between outcomes. Balancing these objectives is made more complex in the case of multispecies and multigear fisheries. In this paper, we develop a bioeconomic model that captures the key elements of such a fishery to test a range of potential harvest strategies to provide insights into how economic target reference points could lead to both desirable and undesirable management outcomes (e.g. discards). The model is developed as a long‐run optimisation model to identify target reference points to achieve multispecies maximum economic yield, and a dynamic recursive optimisation model, which includes more realistic representation of fishers’ behaviour, such as discards and trading of under‐caught species quotas. The potential economic, social and ecological impacts are evaluated using data envelopment analysis (DEA). The results suggest that the use of proxy target reference points can result in short‐term economic benefits at the cost of slower stock recovery and higher discarding. Limiting the number of species subject to quota controls may also prove beneficial in multispecies fisheries, while ensuring quota markets are efficient is likely to produce benefits irrespective of the harvest strategy adopted.     

市政工程造价预结算审核要点与解决对策

在市政工程造价管理和质量控制过程中,相关单位必须重视预结算审核工作,即严格按照我国相关法律法规和相关要求,对预结算加以全面核算,及时发现预结算中存在的问题,且严格监控整个市政工程的建设过程,对市政工程进行科学合理的目标管理,从而有效保证市政工程建设的正常开展。本文主要阐述市政工程造价预结算审核要点,并结合存在的问题提出切实可行的解决对策。     

Automatic extraction of 1D barcodes from video scans for drone-assisted inventory management in warehousing applications

The widespread use of barcodes has significantly contributed to accurate, efficient and economic inventory management in warehouses and distribution centres. However, its efficiency has always been limited by the primary method of reading barcodes with a handheld laser scanner. Compared with this reading by line-of-sight at close proximity, vision-based barcode reading algorithms can further improve efficiency, particularly if accompanied by automated data collection platforms such as drones. This paper introduces algorithms that are able to automatically extract barcodes from video data, and verifies their feasibility and promise for inventory management in warehousing applications. Three key techniques corresponding to different recognition levels are proposed: For a known barcode region, a Harris corner detector and Hough transform-based algorithm is applied to quickly estimate the angle by which the frame area needs to rotate to orient the bars vertically for information extraction. Then, the idea of exploiting connectivity and geometry property of barcode areas is proposed to directly recognise multiple barcode regions in a single video frame to eliminate reading difficulties resulting from interactive influence of multiple juxtaposed barcodes, and to save computation time by only processing frame areas of interest for valid barcodes. In addition, a histogram difference-based fast extraction strategy is designed to further improve efficiency by reducing duplicate information processing. Finally, the performance of each technique is evaluated by analysing video data from a large logistics warehouse, demonstrating satisfactory performance in inventory management applications.     

Points mechanisms and rewards programs

I study points programs, such as frequent flyer and other rewards programs, as a revenue management tool. I develop a two‐period contracting model where a capacity‐constrained firm faces consumers who privately learn their valuations over time. The firm cannot commit to long‐term contracts, but it can commit to allocate any unsold capacity through a points program. This points scheme creates an endogenous and type‐dependent outside option for consumers, which generates novel incentives in the firm's pricing problem. It induces the firm to screen less ex interim, and to offer lower equilibrium prices, reversing the intuition of demand cannibalization.     

高层剪力墙施工技术要点研究

随着高层建筑的增多,建筑施工质量引起人们的热切关注,本文结合高层施工中钢筋工程、模板工程的建筑要素,深入探讨高层剪力墙在施工过程中的技术要点,进一步提高高层建筑施工的水平。