Efficient Methods for Automated Multi-Issue Negotiation: Negotiating over a Two-Part Tariff

In this article, we consider the novel approach of a seller and customer negotiating bilaterally about a two-part tariff, using autonomous software agents. An advantage of this approach is that win-win opportunities can be generated while keeping the problem of preference elicitation as simple as possible. We develop bargaining strategies that software agents can use to conduct the actual bilateral negotiation on behalf of their owners. We present a decomposition of bargaining strategies into concession strategies and Pareto-efficient-search methods: Concession and Pareto-search strategies focus on the conceding and win-win aspect of bargaining, respectively. An important technical contribution of this article lies in the development of two Pareto-search methods. Computer experiments show, for various concession strategies, that the respective use of these two Pareto-search methods by the two negotiators results in very efficient bargaining outcomes while negotiators concede the amount specified by their concession strategy

Market-based Recommendation: Agents that Compete for Consumer Attention

The amount of attention space available for recommending suppliers to consumers on e-commerce sites is typically limited. We present a competitive distributed recommendation mechanism based on adaptive software agents for efficiently allocating the 'consumer attention space', or banners. In the example of an electronic shopping mall, the task is delegated to the individual shops, each of which evaluates the information that is available about the consumer and his or her interests (e.g. keywords, product queries, and available parts of a profile). Shops make a monetary bid in an auction where a limited amount of 'consumer attention space' for the arriving consumer is sold. Each shop is represented by a software agent that bids for each consumer. This allows shops to rapidly adapt their bidding strategy to focus on consumers interested in their offerings. For various basic and simple models for on-line consumers, shops, and profiles, we demonstrate the feasibility of our system by evolutionary simulations as in the field of agent-based computational economics (ACE). We also develop adaptive software agents that learn bidding strategies, based on neural networks and strategy exploration heuristics. Furthermore, we address the commercial and technological advantages of this distributed market-based approach. The mechanism we describe is not limited to the example of the electronic shopping mall, but can easily be extended to other domains

Seasonal changes in gravity wave activity measured by lidars at mid-latitudes

More than 230 nights of temperature measurements between 1 and 105 km have been performed at the Leibniz-Institute of Atmospheric Physics in Kühlungsborn with a combination of two different lidars, i.e. a Rayleigh-Mie-Raman lidar and a potassium lidar. About 1700 h of measurements have been collected between 2002 and 2006. Apart from some gaps due to the adverse weather conditions the measurements are well distributed throughout the year. Comprehensive information about the activity of medium- and low-frequency gravity waves was extracted from this data set. The dominating vertical wavelengths found are between 10 and 20 km and do not show any seasonal variation. In contrast the temperature fluctuations due to gravity waves experience a clear annual cycle with a maximum in winter. The most significant differences exist around 60 km where the fluctuations in winter are more than two times larger than they are in summer. Only small seasonal differences are observed above 90 km and below 35 km. Generally, the fluctuations grow from about 0.5 K up to 8 K between 20 and 100 km. Damping of waves is observed at nearly all altitudes and in all seasons. The planetary wave activity shows a similar structure in altitude and season as the gravity wave activity which indicates that similar mechanisms influencing different scales. Combining the monthly mean temperatures and the fluctuations we show that the transition between winter and summer season and vice versa seems to start in the mesopause region and to penetrate downward

LITOS - A new balloon-borne instrument for fine-scale turbulence soundings in the stratosphere

We have developed a new compact balloon payload called LITOS (Leibniz-Institute Turbulence Observations in the Stratosphere) for high resolution wind turbulence soundings in the stratosphere up to 35 km altitude. The wind measurements are performed using a constant temperature anemometer (CTA) with a vertical resolution of ∼2.5 mm, i.e. 2 kHz sampling rate at 5 m/s ascent speed. Thereby, for the first time, it is possible to study the entire turbulence spectrum down to the viscous subrange in the stratosphere. Including telemetry, housekeeping, batteries and recovery unit, the payload weighs less than 5 kg and can be launched from any radiosonde station. Since autumn 2007, LITOS has been successfully launched several times from the Leibniz-Institute of Atmospheric Physics (IAP) in Kühlungsborn, Germany (54° N, 12° E). Two additional soundings were carried out in 2008 and 2009 in Kiruna, Sweden (67° N, 21° E) as part of the BEXUS program (Balloon-borne EXperiments for University Students). We describe here the basic principle of CTA measurements and prove the validity of this method in the stratosphere. A first case study allows a clear distinction between non-turbulent regions and a turbulent layer with a thickness of some tens of meters. Since our measurements cover the transition between the inertial and viscous subrange, energy dissipation rates can be calculated with high reliability

Seasonal variation of nocturnal temperatures between 1 and 105 km altitude at 54° N observed by lidar

Temperature soundings are performed by lidar at the mid-latitude station of Kühlungsborn (Germany, 54° N, 12° E). The profiles cover the complete range from the lower troposphere (~1 km) to the lower thermosphere (~105 km) by simultaneous and co-located operation of a Rayleigh-Mie-Raman lidar and a potassium resonance lidar. Observations have been done during 266 nights between June 2002 and July 2007, each of 3–15 h length. This large and unique data set provides comprehensive information on the altitudinal and seasonal variation of temperatures from the troposphere to the lower thermosphere. The remaining day-to-day-variability is strongly reduced by harmonic fits at constant altitude levels and a representative data set is achieved. This data set reveals a two-level mesopause structure with an altitude of about 86–87 km (~144 K) in summer and ~102 km (~170 K) during the rest of the year. The average stratopause altitude is ~48 km throughout the whole year, with temperatures varying between 258 and 276 K. From the fit parameters amplitudes and phases of annual, semi-annual, and quarter-annual variations are derived. The amplitude of the annual component is largest with amplitudes of up to 30 K in 85 km, while the quarter-annual variation is smallest and less than 3 K at all altitudes. The lidar data set is compared with ECMWF temperatures below about 70 km altitude and reference data from the NRLMSISE-00 model above. Apart from the temperature soundings the aerosol backscatter ratio is measured between 20 and 35 km. The seasonal variation of these values is presented here for the first time

Ten-year climatology of potassium number density at 54° N, 12° E

In the years from 2002 to 2012 potassium densities observations were performed in the mesopause region at Kühlungsborn using a potassium Doppler lidar. The 10-year diurnal data set comprises 5090 h of potassium number densities at 741 days with 25.2% under full daylight conditions. Potassium number densities show a clear semi-annual variation with two broad maxima reoccurring every year. The first maximum occurs in summer and lasts for about 4 months (May–August) with number densities up to 60 atoms/cc. The second maximum is observed from early December to late February with densities up to 30 atoms/cc. Both the peak density and the column density are higher at solstices than at equinoxes. The large data set shows little variation of the mean layer over the 10 years

Temporal variability of tidal and gravity waves during a record long 10-day continuous lidar sounding

Gravity waves (GWs) as well as solar tides are a key driving mechanism for the circulation in the Earth's atmosphere. The propagation of gravity waves is strongly affected by tidal waves as they modulate the mean background wind field and vice versa, which is not yet fully understood and not adequately implemented in many circulation models. The daylight-capable Rayleigh–Mie–Raman (RMR) lidar at Kühlungsborn (54° N, 12° E) typically provides temperature data to investigate both wave phenomena during one full day or several consecutive days in the middle atmosphere between 30 and 75 km altitude. Outstanding weather conditions in May 2016 allowed for an unprecedented 10-day continuous lidar measurement, which shows a large variability of gravity waves and tides on timescales of days. Using a one-dimensional spectral filtering technique, gravity and tidal waves are separated according to their specific periods or vertical wavelengths, and their temporal evolution is studied. During the measurement period a strong 24 h wave occurs only between 40 and 60 km and vanishes after a few days. The disappearance is related to an enhancement of gravity waves with periods of 4–8 h. Wind data provided by ECMWF are used to analyze the meteorological situation at our site. The local wind structure changes during the observation period, which leads to different propagation conditions for gravity waves in the last days of the measurement period and therefore a strong GW activity. The analysis indicates a further change in wave–wave interaction resulting in a minimum of the 24 h tide. The observed variability of tides and gravity waves on timescales of a few days clearly demonstrates the importance of continuous measurements with high temporal and spatial resolution to detect interaction phenomena, which can help to improve parametrization schemes of GWs in general circulation models

A study of the dissociative recombination of CaO + with electrons: Implications for Ca chemistry in the upper atmosphere

The dissociative recombination of CaO+ ions with electrons has been studied in a flowing afterglow reactor. CaO+ was generated by the pulsed laser ablation of a Ca target, followed by entrainment in an Ar+ ion/electron plasma. A kinetic model describing the gas-phase chemistry and diffusion to the reactor walls was fitted to the experimental data, yielding a rate coefficient of (3.0 ± 1.0) × 10¯⁷ cm³ molecule¯¹ s¯¹ at 295 K. This result has two atmospheric implications. First, the surprising observation that the Ca+/Fe+ ratio is ~8 times larger than Ca/Fe between 90 and 100 km in the atmosphere can now be explained quantitatively by the known ion-molecule chemistry of these two metals. Second, the rate of neutralization of Ca+ ions in a descending sporadic E layer is fast enough to explain the often explosive growth of sporadic neutral Ca layers

Environmental Health Program Performance and its Relationship with Environment-Related Disease in Florida

This study used a unique approach to examine Florida county health department environmental health (EH) program performance of the 10 Essential Environmental Public Health Services (EEPHS) and its relationship with environment- related disease, described by enteric disease rates. Correlation analysis tested the association between performance of each EEPHS and five different enteric disease rates, while multivariate regression analysis further examined the relationships while considering program organizational characteristics as potential confounders. Correlation analysesrevealed cryptosporidiosis was associated with EEPHS 2 diagnose (Τb = .195, p = .027) and EEPHS 8 workforce (Τb= .234, p = .006), and salmonellosis with EEPHS 4 mobilize (Τb = .179, p = .042) and EEPHS 6 enforce (Τb = .201, p = .020). Multivariate regression results showed EEPHS 2 diagnose (p = .04) and EEPHS 4 mobilize (p = .00) had statistically significant associations with cryptosporidiosis and salmonellosis, respectively, and suggested that improved performance of these two EEPHS may have decreased disease incidence. EH programs may benefit from improving the performance of EEPHS to address the incidence of certain enteric diseases. Continued efforts to develop a robust understanding of EH program performance and its impact on environment-related disease could enhance EH services delivery and ability to improve health outcomes