A linear programming-based method for job shop scheduling

We present a decomposition heuristic for a large class of job shop scheduling problems. This heuristic utilizes information from the linear programming formulation of the associated optimal timing problem to solve subproblems, can be used for any objective function whose associated optimal timing problem can be expressed as a linear program (LP), and is particularly effective for objectives that include a component that is a function of individual operation completion times. Using the proposed heuristic framework, we address job shop scheduling problems with a variety of objectives where intermediate holding costs need to be explicitly considered. In computational testing, we demonstrate the performance of our proposed solution approach

Ownership and control in a competitive industry

We study a differentiated product market in which an investor initially owns a controlling stake in one of two competing firms and may acquire a non-controlling or a controlling stake in a competitor, either directly using her own assets, or indirectly via the controlled firm. While industry profits are maximized within a symmetric two product monopoly, the investor attains this only in exceptional cases. Instead, she sometimes acquires a noncontrolling stake. Or she invests asymmetrically rather than pursuing a full takeover if she acquires a controlling one. Generally, she invests indirectly if she only wants to affect the product market outcome, and directly if acquiring shares is profitable per se. --differentiated products,separation of ownership and control,private benefits of control

Leitthema 4: Solare UV-B-Strahlung. Teilvorhaben: Charakterisierung von Wolken und Aerosolen durch Lidar-Fernerkundung hinsichtlich des UV-Strahlungstransfers Abschlussbericht

The investigations characterize aerosols and clouds over Garmisch-Partenkirchen by lidar remote sensing, and support the interpretation of measurements of the transfer of UV radiation. Extensive tests of calibration procedures were performed, and the lidar system was modified to meet the requirements. The focal point were measurements accompanying the CUVRA (Characteristics of the UV Radiation field in the Alps) campaign at IFU in March 1999. 767 lidar measurements in two wavelength channels were performed on 12 days during this campaign. Aerosol and cloud situations were characterized by determining lower and upper layer heights (time resolution down to 1 minute, height resolution down to 15 meters), multi layer situations from ground to the tropopause region (up to 5 aerosol and cloud layers), optical depths at 532 nm and 355 nm (range 0.01 to 3), wavelength dependences of the optical depth between 532 nm and 355 nm (range of wavelength exponent 0 to -2), and lidar ratios (extinction/backscatter) at 532 nm (range 20 to 38). (orig.)Die Untersuchungen charakterisieren Aerosole und Wolken ueber Garmisch-Partenkirchen durch Lidar-Fernerkundung und dienen der Interpretation von Messungen des UV-Strahlungsflusses. Hierzu waren umfangreiche Arbeiten zum Testen von Eichverfahren notwendig, ebenso wie Modifizerungen des Lidarsystems. Schwerpunkt der Untersuchungen waren Messungen waehrend der CUVRA (Characteristics of the UV Radiation field in the Alps) Messkampagne im Maerz 1999 am IFU. Waehrend dieser Kampagne wurden an 12 Messtagen 767 Lidarmessungen in jeweils zwei Wellenlaengenkanaelen durchgefuehrt. Die Aerosol- und Wolkensituationen wurden charakterisiert durch die Bestimmung von Schichtunter-und obergrenzen (Zeitaufloesung bis zu 1 Minute, Hoehenaufloesung bis zu 15 m), der Mehrschichtigkeit vom Boden bis zum Tropopausenbereich (bis zu 5 Aerosol-und Wolkenschichten), der optischen Dicken bei 532 nm und 355 nm (Bereich 0.01 bis 3), der Wellenlaengenabhaengigkeit der optischen Dicke zwischen 532 nm und 355 nm (Bereich des Exponenten 0 bis -2), und des Lidarverhaeltnisses (Extinktion/Rueckstreuung) bei 532 nm (Bereich 20 bis 38). (orig.)SIGLEAvailable from TIB Hannover: F01B398+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Tropospheric aerosol layers after a cold front passage in January 2000 as observed at several stations of the German Lidar Network

Using the German Lidar Network, we analysed 2 years of lidar observations of aerosol layers. Here we report in particular on a cold front event in January 2000 with Rayleigh/Mie/Raman lidar measurements taken both in the boundary layer as well as in the free troposphere at four different sites. After the cold front passage, and while the air mass travelled from northern to southern Germany, the aerosol backscatter coefficient increased in the lower troposphere but not in the free troposphere. Behind the front, an aerosol layer was observed in the free troposphere at all stations. To characterize changes in the aerosol layer as it moved from northern to southern Germany, backscatter profiles measured at Kuhlungsborn and Hamburg were compared with profiles at Leipzig and Garmisch-Partenkirchen, respectively. This case study shows that an aerosol layer can persist in the free troposphere over a period of a few days. From calculated backward trajectories, we conclude that the air mass was lifted from the boundary layer, most likely 2-3 days before the cold front reached the lidar stations in Germany. We also compare the results of different trajectory models with respect to the origin of the aerosol layer. They indicate continental aerosols from the center of the North American continent, which is consistent with particle size inversion results from the lidar backscaner data. (C) 2002 Elsevier Science B.V. All rights reserved.Peer reviewe