Some factors affecting agricultural production .and productivity in Iraq including selected climate variables and crops

In this study of factors affecting Iraqi agricultural production and productivity, it has been found essential to deal both with socioeconomic and technical factors on the one hand and environmental conditons on the other. The ultimate objective of this study is to assess the impact of selected climatic factors on the production and productivity of some principal crops. Such assessment, however, cannot be achieved in isolation from the influence of the socio-economic and technical factors. Considerable variability over time of the latter factors, caused by specific institutional changes such as the land reform of 1958, resulted in changes in agricultural conditions as a whole. Therefore, in Chapters Two to Nine are examined the national and regional conditions of Iraqi agriculture during the 1950-1975 period, i.e. planning and investment, land utilization, land tenure system and land reform, agricultural cooperatives and other organizations, new input factors including farm machinery and, finally, water resources and irrigation methods. The inescapable conclusion of this section of the study is that there were no significant medium or long-term improvement trends in the yields of principal crops despite varying but considerable additional inputs and planning attention. Moreover, the controls exerted by climate and weather appear crucial factors in both the irrigated and rainfed area. In Chapters Ten and Eleven we therefore turn to a direct examination of climatic and weather factors. In Chapters Twelve and Thirteen a study is made of the relationship between selected weather variables, i.e. rainfall, temperature and relative humidity, and wheat and barley yield. These two crops were chosen because of their importance to Iraqi agriculture as a whole, and in particular to the rainfed area of northern Iraq where environmental modifications by man are least strong. The first point appearing from this analysis shows that yields of these two crops are significantly affected by climatic and weather factors during specific periods within the growing season. The significance of statistical correlations between yields and certain critical climatic factors appear sufficiently valid for crop forecasting with a certain degree of accuracy. As a by-product of this analysis, it appears that there was a significant dislocation period following the implementation of land reform measures. In conclusion, it is clear that agricultural production and productivity must be dealt with in the context of a whole set of factors, socio-economic, technical and environmental, if significant developments in agriculture and rural welfare are to be achieved

Quantum phase transitions in photonic cavities with two-level systems

Systems of coupled photonic cavities have been predicted to exhibit quantum phase transitions by analogy with the Hubbard model. To this end, we have studied topologies of few (up to six) photonic cavities each containing a single two-level system. Quantum phase space diagrams are produced for these systems, and compared to mean-field results. We also consider finite effective temperature, and compare this to the notion of disorder. We find the extent of the Mott lobes shrink analogously to the conventional Bose-Hubbard model.Comment: 11 pages, 11 figures, updated typo

Spin Readout and Initialization in a Semiconductor Quantum Dot

Electron spin qubits in semiconductors are attractive from the viewpoint of long coherence times. However, single spin measurement is challenging. Several promising schemes incorporate ancillary tunnel couplings that may provide unwanted channels for decoherence. Here, we propose a novel spin-charge transduction scheme, converting spin information to orbital information within a single quantum dot by microwave excitation. The same quantum dot can be used for rapid initialization, gating, and readout. We present detailed modeling of such a device in silicon to confirm its feasibility.Comment: Published versio

Valley Splitting Theory of SiGe/Si/SiGe Quantum Wells

We present an effective mass theory for SiGe/Si/SiGe quantum wells, with an emphasis on calculating the valley splitting. The theory introduces a valley coupling parameter, $v_v$, which encapsulates the physics of the quantum well interface. The new effective mass parameter is computed by means of a tight binding theory. The resulting formalism provides rather simple analytical results for several geometries of interest, including a finite square well, a quantum well in an electric field, and a modulation doped two-dimensional electron gas. Of particular importance is the problem of a quantum well in a magnetic field, grown on a miscut substrate. The latter may pose a numerical challenge for atomistic techniques like tight-binding, because of its two-dimensional nature. In the effective mass theory, however, the results are straightforward and analytical. We compare our effective mass results with those of the tight binding theory, obtaining excellent agreement.Comment: 13 pages, 7 figures. Version submitted to PR

Assessment of the Robustness of a Fixtureless Inspection Method for Nonrigid Parts Based on a Verification and Validation Approach

The increasing practical use of computer-aided inspection (CAI) methods requires assessment of their robustness in different contexts. This can be done by quantitatively comparing estimated CAI results with actual measurements. The objective is comparing the magnitude and dimensions of defects as estimated by CAI with those of the nominal defects. This assessment is referred to as setting up a validation metric. In this work, a new validation metric is proposed in the case of a fixtureless inspection method for nonrigid parts. It is based on using a nonparametric statistical hypothesis test, namely the Kolmogorov–Smirnov (K–S) test. This metric is applied to an automatic fixtureless CAI method for nonrigid parts developed by our team. This fixtureless CAI method is based on calculating and filtering sample points that are used in a finite element nonrigid registration (FENR). Robustness of our CAI method is validated for the assessment of maximum amplitude, area, and distance distribution of defects. Typical parts from the aerospace industry are used for this validation and various levels of synthetic measurement noise are added to the scanned point cloud of these parts to assess the effect of noise on inspection results