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The primary driver of operating costs in natural gas processes is the energy consumption of the compression system. Multistage compression configurations are commonly employed and hence play a vital role in optimization of natural gas processes. In this study, a generalized disjunctive programming model for multistage compression is formulated. The model is useful for both synthesis and optimization of multistage compression configurations. By using this approach, we further seek improvements in shaft work savings. The model relies on thermodynamic equations and is designed to minimize the consumption of shaft work. The model is handled by employing the logic-based branch and bound algorithm, eliminating the need for explicit conversion into a MINLP, which in turn leads to improved convergence and faster computational performance. The model solution yields optimal pressure levels, and hence stage shaft work consumptions. A case study of multistage compression for a prior optimized single mixed refrigerant (SMR) process obtained from literature is used to test the proposed model. The model’s outcomes are validated through simulation using the Aspen Hysys software. Savings in shaft work of atmost 0.0088%, 0.4433%, and 1.2321% are obtained for the two, three, and four stage compression systems respectively against the optimized base cases from literature.

INTRODUCTION: lack of knowledge of where to obtain correct family planning (FP) information and methods can be a critical barrier to eventual uptake of FP services. We assessed knowledge, sources and use of FP methods among women of reproductive age in rural Uganda. METHODS: this secondary analysis uses data from a larger cross-sectional study conducted to measure changes in perceptions towards long-term and reversible contraceptive use among 2,033 women of reproductive age (15-49years) resident in 34 districts of Uganda. Both users and non-users of FP methods were interviewed. Data were analyzed using STATA statistical software, version 12. RESULTS: majority of the women were less than 30 years of age (64.3%). Nearly three-quarters were married (73.1%), 51.1% had primary education and more than half (57%) were engaged in employment. Knowledge of FP methods was universal (98.1%). Clinic providers (60.4%), friends (56.9%) and the media (51.3%) were the most trusted sources of contraceptive information. Government (27.6%) and private (21.1%) health facilities were the main sources of modern FP methods. Sixty two per cent of women reported current use of any FP method. Among non-users of FP, injectables (50.4%), implants (22.8%) and pills (20.2%) were the most preferred FP methods. CONCLUSION: our findings show that knowledge of FP methods is almost universal and that six in ten women use any FP method. Clinic providers, friends and the media are the most trusted sources of FP information. Government and private health facilities are the main sources of FP services.