A query processor QP uses the rules in a rule base to reduce a given query to a series of attempt... more A query processor QP uses the rules in a rule base to reduce a given query to a series of attempted retrievals from a database of facts. The Qp's expected cost is the average time it requires to find an answer, averaged over its anticipated set of queries. This cost depends on Qp's strategy, which specifies the order in which it considers the possible rules and retrievals. This paper provides two related learning algorithms, PIB and PAO, for improving the QP's strategy, i.e., for producing new strategies with lower expected costs. Each algorithm first monitors the Qp's operations over a set of queries, observing how often each path of rules leads to a sufficient set of successful retrievals, and then uses these statistics to suggest a new strategy. PIB hill-climbs to strategies that are, with high probability, successively better; and PAO produces a new strategy that probably is approximately optimal. We describe how to implement both learning systems unobtrusively, discuss their inherent time and space complexities, and use methods from mathematical statistics to prove their correctness. We also discuss additional applications of these approaches to several other database tasks.
This study assessed the optimal conditions for PHA production using saponified fatty acid, derive... more This study assessed the optimal conditions for PHA production using saponified fatty acid, derived from sunflower oil (SO). A fed-batch reactor was used to produce PHA. A mixture of sewage and semi-treated oil palm effluent from a facultative pond was cultured for six months to obtain a steady-state condition. The culture was then transferred to the fed-batch system. SO mainly contains long-chain-fatty-acid (LCFA) with unsaturated fatty acid fractions of C 14:1 -C 18:3 , therefore the PHA production was assessed under feast-famine condition. The main purpose of supplementing saponified SO was to improve the production of PHA constituents (copolymer of hydroxyl-unit) such as hydroxybutyrates (HBs), hydroxyvalerates (HVs) and hydroxyhexanoates (HHs) in mixed cultures. Fed-batch operation under aerobic-mixed cultures increased the PHA production up to 33% of the dried cell. Although sludge submitted to aerobic condition in mixed cultures could improve the PHA production, the production rates are still low. This study found that the HBs constituent in the sludge is always higher compared to HVs and HHs. Saponified SO has high specific PHA storage rates (q p feast = 0.5 C-mol/C-mol. h) which are comparable to other vegetable oils (e.g. corn oil, soy bean oil, etc.) Abstrak: Kajian telah dijalankan bagi menilai keadaan optima penghasilan PHA menggunakan asid lemak tersaponifikasi yang diubahsuai daripada minyak bunga matahari (SO). Sebuah reaktor suapan-kelompok telah digunakan untuk menghasilkan PHA. Campuran daripada airsisa dan efluen separa olahan daripada kolam pengoksidaan dikulturkan selama enam bulan untuk menghasilkan keadaan 'steady-state'. Kultur tersebut kemudiannya dipindahkan ke sistem suapan-kelompok. SO mengandungi asid lemak rantaian panjang dalam kumpulan asid lemak tak tepu (C 14:1 -C 18:3 ), oleh itu penghasilan PHA telah diteliti semasa keadaan 'feast-famine'. Tujuan utama membekalkan SO yang tersaponifikasi adalah untuk menambah kualiti kandungan PHA (kopolimer unit hidroksil) seperti hidroksibutirat (HB), hidroksivalerat (HV) dan hidroksiheksanoat (HH) di dalam kultur campuran. Operasi suapan berkelompok menggunakan kultur campuran secara aerobik dapat meningkatkan penghasilan PHA sehingga 33% daripada Malaysian Journal of Civil Engineering 18(2) : 109-128 (2006) 110 berat sel kering. Walaupun enapcemar yang dikulturkan secara campuran dapat meningkatkan kualiti penghasilan PHA, kadarnya masih rendah. Kajian ini mendapati kandungan HB dalam enapcemar sentiasa lebih tinggi berbanding HV dan HH. SO yang tersaponifikasi mempunyai kadar simpanan spesifik PHA yang tinggi (q p feast = 0.5 C-mol/C-mol. h) dan setanding dengan minyak sayuran lain (seperti minyak jagung, minyak soya, dan sebagainya) Kata Kunci: Kultur Campuran Aerobik; Kondungan PHA; Asid Lemak Tersaponifikasi; Minyak Bunga Matahari.
A query processor QP uses the rules in a rule base to reduce a given query to a series of attempt... more A query processor QP uses the rules in a rule base to reduce a given query to a series of attempted retrievals from a database of facts. The Qp's expected cost is the average time it requires to find an answer, averaged over its anticipated set of queries. This cost depends on Qp's strategy, which specifies the order in which it considers the possible rules and retrievals. This paper provides two related learning algorithms, PIB and PAO, for improving the QP's strategy, i.e., for producing new strategies with lower expected costs. Each algorithm first monitors the Qp's operations over a set of queries, observing how often each path of rules leads to a sufficient set of successful retrievals, and then uses these statistics to suggest a new strategy. PIB hill-climbs to strategies that are, with high probability, successively better; and PAO produces a new strategy that probably is approximately optimal. We describe how to implement both learning systems unobtrusively, discuss their inherent time and space complexities, and use methods from mathematical statistics to prove their correctness. We also discuss additional applications of these approaches to several other database tasks.
This study assessed the optimal conditions for PHA production using saponified fatty acid, derive... more This study assessed the optimal conditions for PHA production using saponified fatty acid, derived from sunflower oil (SO). A fed-batch reactor was used to produce PHA. A mixture of sewage and semi-treated oil palm effluent from a facultative pond was cultured for six months to obtain a steady-state condition. The culture was then transferred to the fed-batch system. SO mainly contains long-chain-fatty-acid (LCFA) with unsaturated fatty acid fractions of C 14:1 -C 18:3 , therefore the PHA production was assessed under feast-famine condition. The main purpose of supplementing saponified SO was to improve the production of PHA constituents (copolymer of hydroxyl-unit) such as hydroxybutyrates (HBs), hydroxyvalerates (HVs) and hydroxyhexanoates (HHs) in mixed cultures. Fed-batch operation under aerobic-mixed cultures increased the PHA production up to 33% of the dried cell. Although sludge submitted to aerobic condition in mixed cultures could improve the PHA production, the production rates are still low. This study found that the HBs constituent in the sludge is always higher compared to HVs and HHs. Saponified SO has high specific PHA storage rates (q p feast = 0.5 C-mol/C-mol. h) which are comparable to other vegetable oils (e.g. corn oil, soy bean oil, etc.) Abstrak: Kajian telah dijalankan bagi menilai keadaan optima penghasilan PHA menggunakan asid lemak tersaponifikasi yang diubahsuai daripada minyak bunga matahari (SO). Sebuah reaktor suapan-kelompok telah digunakan untuk menghasilkan PHA. Campuran daripada airsisa dan efluen separa olahan daripada kolam pengoksidaan dikulturkan selama enam bulan untuk menghasilkan keadaan 'steady-state'. Kultur tersebut kemudiannya dipindahkan ke sistem suapan-kelompok. SO mengandungi asid lemak rantaian panjang dalam kumpulan asid lemak tak tepu (C 14:1 -C 18:3 ), oleh itu penghasilan PHA telah diteliti semasa keadaan 'feast-famine'. Tujuan utama membekalkan SO yang tersaponifikasi adalah untuk menambah kualiti kandungan PHA (kopolimer unit hidroksil) seperti hidroksibutirat (HB), hidroksivalerat (HV) dan hidroksiheksanoat (HH) di dalam kultur campuran. Operasi suapan berkelompok menggunakan kultur campuran secara aerobik dapat meningkatkan penghasilan PHA sehingga 33% daripada Malaysian Journal of Civil Engineering 18(2) : 109-128 (2006) 110 berat sel kering. Walaupun enapcemar yang dikulturkan secara campuran dapat meningkatkan kualiti penghasilan PHA, kadarnya masih rendah. Kajian ini mendapati kandungan HB dalam enapcemar sentiasa lebih tinggi berbanding HV dan HH. SO yang tersaponifikasi mempunyai kadar simpanan spesifik PHA yang tinggi (q p feast = 0.5 C-mol/C-mol. h) dan setanding dengan minyak sayuran lain (seperti minyak jagung, minyak soya, dan sebagainya) Kata Kunci: Kultur Campuran Aerobik; Kondungan PHA; Asid Lemak Tersaponifikasi; Minyak Bunga Matahari.
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