Comparing software design methodologies through process modeling

Recently, the importance of consolidating existing software engineering approaches and concepts has been well recognized by the software engineering community [Boa90]. We believe that study of Software Design Methodologies (SDMs) is an excellent place to start. To achieve this, we must be able to objectively and systematically compare SDMs.Quite a number of SDMs have been developed and compared over the past two decades. An accurate comparison aids in codifying, enhancing and integrating SDMs. However, after analyzing the existing comparisons, we found that these comparisons are often based largely upon the experiences of the practitioners and the intuitive understandings of the authors. Consequently, these comparisons are subjective and affected by application domains. We also analyzed a number of comparisons which use quasinormal approaches to comparing SDMs. We found that these comparisons are often based on hypothesizing features required by the design process and software design problems. In order to compare SDMs more scientifically, in this thesis we introduce a systematic approach (called CDM (Comparing Design Methodologies)) to objectively comparing SDMs. We hope that using CDM will lead to precise, explicit and complete comparisons.CDM is based on modeling SDMs and classifying their components (e.g. guidelines and notations). Modeling SDMs entails decomposing them into components. The classification of the components illustrates which components address similar design issues and/or have similar structures. Similar components then may be further modeled to aid in understanding more precisely their similarities and differences. The models of the SDMs are also used as the bases for conjectures and conclusions about the differences between the SDMs.Two key components required by CDM are 1) a fair Base Framework (BF) to classify parts of SDMs and a comprehensive Modeling Formalism (MF) to model all these parts. In this thesis we address these two problems by suggesting an evolutionary strategy for developing such a BF and MF. Then we present the BF and MF we have developed using this strategy, and demonstrate how they have been and can be used. Further we evaluate the BF and MF based on their applications and suggest how they might be enhanced. In doing this, we intend to illustrate that increasingly fair BFs and MFs can be developed by using this development strategy.We believe that this sort of iterative evolutionary development of key framework and modeling formalisms is consistent with the ways in which more mature scientific disciplines operate. Thus, we hope that this effort indicates a way in which software engineering can begin to grow into a mature scientific discipline. Further, we suggest that this evolutionary development of BFs and MFs should be a community-wide activity.In this thesis we demonstrate this approach by using it to compare six SDMs (JSD [Jac83], Booch's Object Oriented Design (BOOD) [Boo86], RDM [PC86], SD [YC79, SMC74], LCP [War76], and DSSD [Orr77]). We compared our SDM comparisons against other comparisons obtained using other approaches. The results of this comparison demonstrate that process modeling [Ost87, KH88] is valuable as a powerful tool in analysis of software development approaches. Besides, the SDM comparisons result, we obtained through this effort are by themselves valuable for understanding software design activities and SDMs

A Study of Single-vendor and Multiple-retailers Pricing-Ordering Strategy under Group-Buying Online Auction

The supplier and buyers, with different objectives and self-interest, are separate economic entities acting independently and opportunistically to maximize their individual profits. In this paper, a GBA model in the B2B market is studied, where one supplier faces 2 different retailers, who cooperate in the order decision making. Firstly, the optimal ordering decision of the retailers was analyzed. Then, from the perspective of the supplier, the optimal pricing strategy of the supplier is also studied. Finally, it is concluded that the group buying online auction is a useful and efficient pricing mechanism in the B2B e-market, under which, all members of the supply chain will improve their payoffs

Effects of Hf, B, Cr and Zr alloying on mechanical properties and oxidation resistance of Nb-Si based ultrahigh temperature alloy

Multi-component Nb-Si based ultrahigh temperature alloys were prepared by vacuum non-consumable arc melting. The effects of Hf, B, Zr and Cr alloying on the phase selection, phase stability, both non-equilibrium and equilibrium microstructure, room-temperature fracture toughness, hardness and oxidation resistance at 1250 oC of the alloys have been investigated and estimated systematically. The results show that the addition of B or Cr promotes the formation of hypereutectic structures. The alloying with both Hf and B suppresses the formation of β(Nb,X)5Si3 and promotes the formation of α(Nb,X)5Si3 and γ(Nb,X)5Si3, while the alloying with Cr has no effect on the crystal structures of 5-3 silicides. The room-temperature fracture toughness of the alloys is always degraded by the addition of Cr but almost not influenced by the combined additions of Hf and B. The hardness of 5-3 silicides exhibits a tendency of γ \u3e α \u3e β. The macrohardness of the alloys increases with Cr addition, and it obviously reduces in the presence of Hf after 1450 oC/50 h heat-treatment. The best oxidation-resistant performance has been obtained for the alloy with both B and Cr additions. However, in the presence of B and/or Cr, the oxidation resistance of the alloys has been degraded by further addition of Hf. Both sizes and amounts of primary γ-(Nb, X)5Si3 increase with Zr contents in the alloy. Both adhesion and compactness of the scales are improved effectively by increase in Zr content. The mass gain and thickness of the scale decrease with increase in Zr contents, indicating that Zr addition can improve the oxidation resistance of the alloys significantly. Please click Additional Files below to see the full abstract

Effectively control negative thermal expansion of single-phase ferroelectrics of PbTiO3-(Bi,La)FeO3 over a giant range

Control of negative thermal expansion is a fundamentally interesting topic in the negative thermal expansion materials in order for the future applications. However, it is a challenge to control the negative thermal expansion in individual pure materials over a large scale. Here, we report an effective way to control the coefficient of thermal expansion from a giant negative to a near zero thermal expansion by means of adjusting the spontaneous volume ferroelectrostriction (SVFS) in the system of PbTiO3-(Bi,La) FeO3 ferroelectrics. The adjustable range of thermal expansion contains most negative thermal expansion materials. The abnormal property of negative or zero thermal expansion previously observed in ferroelectrics is well understood according to the present new concept of spontaneous volume ferroelectrostriction. The present studies could be useful to control of thermal expansion of ferroelectrics, and could be extended to multiferroic materials whose properties of both ferroelectricity and magnetism are coupled with thermal expansion

Interaction of serum vitamin B12 and folate with MTHFR genotypes on risk of ischemic stroke

ObjectiveWe evaluated the interaction of serum folate and vitamin B12 with methylenetetrahydrofolate reductase (MTHFR) C677T genotypes on the risk of first ischemic stroke and on the efficacy of folic acid treatment in prevention of first ischemic stroke.MethodsA total of 20,702 hypertensive adults were randomized to a double-blind treatment of daily enalapril 10 mg and folic acid 0.8 mg or enalapril 10 mg alone. Participants were followed up every 3 months.ResultsMedian values of folate and B12 concentrations at baseline were 8.1 ng/mL and 280.2 pmol/L, respectively. Over a median of 4.5 years, among those not receiving folic acid, participants with baseline serum B12 or serum folate above the median had a significantly lower risk of first ischemic stroke (hazard ratio [HR], 0.74; 95% confidence interval [CI], 0.57-0.96), especially in those with MTHFR 677 CC genotype (wild-type) (HR, 0.49; 95% CI, 0.31-0.78). Folic acid treatment significantly reduced the risk of first ischemic stroke in participants with both folate and B12 below the median (2.3% in enalapril-folic acid group vs 3.6% in enalapril-only group; HR, 0.62; 95% CI, 0.46-0.86), particularly in MTHFR 677 CC carriers (1.6% vs 4.9%; HR, 0.24; 95% CI, 0.11-0.55). However, TT homozygotes responded better with both folate and B12 levels above the median (HR, 0.28; 95% CI, 0.10-0.75).ConclusionsThe risk of first ischemic stroke was significantly higher in hypertensive patients with low levels of both folate and B12. Effect of folic acid treatment was greatest in patients with low folate and B12 with the CC genotype, and with high folate and B12 with the TT genotype

Egg consumption associated with all-cause mortality in rural China: A 14-year follow-up study

Background: Dietary recommendations regarding egg intake remain controversial topic for public health. We hypothesized that there was a positive association between egg consumption and all-cause mortality. Methods: To test this hypothesis, we enrolled 9885 adults from a community-based cohort in Anhui Province, China during 2003-05. Egg consumption was assessed by food questionnaire. Stratified analyses were performed for age, sex, body mass index (BMI), blood pressure, smoking, drinking and laboratory tests. Results: After an average follow-up of 14.1 years, 9444 participants were included for analysis. A total of 814 deaths were recorded. Participants\u27 BMI and lipid profile had no significantly difference between three egg consumption groups. BMI was 21.6±2.7 of the whole population, especially BMI\u3e24 was only 17.3%. A bivariate association of egg consumption \u3e6/week with increased all-cause mortality was observed compared with ≤6/week (RR: 1.35, 95% CI: 1.05, 1.73, P = 0.018). A significant interaction was observed for BMI ≥ 21.2 kg/m2 vs. BMI\u3c21.2 kg/m2 (P for interaction: 0.001). No other significant interactions were found. Conclusions: In this study, consuming \u3e6 eggs/week increased risk of all-cause mortality, even among lean participants, especially who with BMI ≥ 21.2 kg/m2. Eggs are an easily accessible and constitute an affordable food source in underdeveloped regions. Consuming \u3c6 eggs/week may be the most suitable intake mode

Achieving blood pressure control targets in hypertensive patients of rural China - A pilot randomized trial

Background: This study aimed to test the feasibility and titration methods used to achieve specific blood pressure (BP) control targets in hypertensive patients of rural China. Methods: A randomized, controlled, open-label trial was conducted in Rongcheng, China. We enrolled 105 hypertensive participants aged over 60 years, and who had no history of stroke or cardiovascular disease. The patients were randomly assigned to one of three systolic-BP target groups: standard: 140 to \u3c 150 mmHg; moderately intensive: 130 to \u3c 140 mmHg; and intensive: \u3c 130 mmHg. The patients were followed for 6 months. Discussion: The optimal target for systolic blood pressure (SBP) lowering is still uncertain worldwide and such information is critically needed, especially in China. However, in China the rates of awareness, treatment and control are only 46.9%, 40.7%, and 15.3%, respectively. It is challenging to achieve BP control in the real world and it is very important to develop population-specific BP-control protocols that fully consider the population\u27s characteristics, such as age, sex, socio-economic status, compliance with medication, education level, and lifestyle. This randomized trial showed the feasibility and safety of the titration protocol to achieve desirable SBP targets (\u3c 150, \u3c 140, and \u3c 130 mmHg) in a sample of rural, Chinese hypertensive patients. The three BP target groups had similar baseline characteristics. After 6 months of treatment, the mean SBP measured at an office visit was 137.2 mmHg, 131.1 mmHg, and 124.2 mmHg, respectively, in the three groups. Home BP and central aortic BP measurements were also obtained. At 6 months, home BP measurements (2 h after drug administration) showed a mean SBP of 130.9 mmHg in the standard group, 124.9 mmHg in the moderately intensive group, and 119.7 mmHg in the intensive group. No serious adverse events were recorded over the 6-month study period. Rates of adverse events, including dry cough, palpitations, and arthralgia, were low and showed no significant differences between the three groups. This trial provided real-world experience and laid the foundation for a future, large-scale, BP target study. Trial registration: Feasibility Study of the Intensive Systolic Blood Pressure Control; ClinicalTrials.gov, ID: NCT02817503. Registered retrospectively on 29 June 2016

Association of folic acid dosage with circulating unmetabolized folic acid in Chinese adults with H-type hypertension: a multicenter, double-blind, randomized controlled trial

BackgroundThere is growing concern regarding elevated levels of circulating unmetabolized folic acid (UMFA) due to excessive intake of folic acid (FA). However, no randomized clinical trial has been conducted to examine the FA-UMFA dose-response relationship.ObjectiveThis study aimed to investigate the FA-UMFA dose-response relationship in Chinese adults with hypertension and elevated homocysteine (H-type hypertension), a population with clear clinical indication for FA treatment.MethodsThe data for this study were derived from a randomized, double-blind, multicenter clinical trial of 8 FA dosages on efficacy of homocysteine (Hcy) lowering. The parent trial had three 3 stages: screening period (2–10 days), run-in period (0–2 weeks, baseline visit), and double-blind treatment period (8 weeks) with follow-up visits at the end of the 2nd, 4th, 6th, and 8th weeks of treatment. Participants were randomly assigned to 8 treatment groups corresponding to FA dosages of 0, 0.4, 0.6, 0.8, 1.2, 1.6, 2.0 mg to 2.4 mg.ResultsThis study included 1,567 Chinese adults aged ≥45 years with H-type hypertension. There was a positive but non-linear association between FA supplementation and UMFA levels in the dosage range of 0 mg to 2.4 mg. In the regression analysis, the coefficients for the linear and quadratic terms of FA dosage were both statistically significant (P < 0.001). Notably, the slope for UMFA was greater for FA dosages >0.8 mg (ß = 11.21, 95% CI: 8.97, 13.45) compared to FA dosages ≤0.8 mg (ß = 2.94, 95% CI: 2.59, 3.29). Furthermore, FA dosages higher than 0.8 mg did not confer additional benefits in terms of increasing 5-methyl tetrahydrofolic acid (5-MTHF, active form of folate) or reducing homocysteine (Hcy).ConclusionIn Chinese adults with H-type hypertension, this study showed a positive, non-linear, dosage-response relationship between FA supplementation ranging from 0 to 2.4 mg and circulating UMFA levels. It revealed that 0.8 mg FA is an optimal dosage in terms of balancing efficacy (increasing 5-MTHF and lowering Hcy) while minimizing undesirable elevation of UMFA.Clinical trial registrationhttps://clinicaltrials.gov/ct2/show/NCT03472508?term=NCT03472508&draw=2&rank=1, identifier NCT03472508

Comparing software design methodologies through process modeling

Recently, the importance of consolidating existing software engineering approaches and concepts has been well recognized by the software engineering community [Boa90]. We believe that study of Software Design Methodologies (SDMs) is an excellent place to start. To achieve this, we must be able to objectively and systematically compare SDMs.Quite a number of SDMs have been developed and compared over the past two decades. An accurate comparison aids in codifying, enhancing and integrating SDMs. However, after analyzing the existing comparisons, we found that these comparisons are often based largely upon the experiences of the practitioners and the intuitive understandings of the authors. Consequently, these comparisons are subjective and affected by application domains. We also analyzed a number of comparisons which use quasinormal approaches to comparing SDMs. We found that these comparisons are often based on hypothesizing features required by the design process and software design problems. In order to compare SDMs more scientifically, in this thesis we introduce a systematic approach (called CDM (Comparing Design Methodologies)) to objectively comparing SDMs. We hope that using CDM will lead to precise, explicit and complete comparisons.CDM is based on modeling SDMs and classifying their components (e.g. guidelines and notations). Modeling SDMs entails decomposing them into components. The classification of the components illustrates which components address similar design issues and/or have similar structures. Similar components then may be further modeled to aid in understanding more precisely their similarities and differences. The models of the SDMs are also used as the bases for conjectures and conclusions about the differences between the SDMs.Two key components required by CDM are 1) a fair Base Framework (BF) to classify parts of SDMs and a comprehensive Modeling Formalism (MF) to model all these parts. In this thesis we address these two problems by suggesting an evolutionary strategy for developing such a BF and MF. Then we present the BF and MF we have developed using this strategy, and demonstrate how they have been and can be used. Further we evaluate the BF and MF based on their applications and suggest how they might be enhanced. In doing this, we intend to illustrate that increasingly fair BFs and MFs can be developed by using this development strategy.We believe that this sort of iterative evolutionary development of key framework and modeling formalisms is consistent with the ways in which more mature scientific disciplines operate. Thus, we hope that this effort indicates a way in which software engineering can begin to grow into a mature scientific discipline. Further, we suggest that this evolutionary development of BFs and MFs should be a community-wide activity.In this thesis we demonstrate this approach by using it to compare six SDMs (JSD [Jac83], Booch's Object Oriented Design (BOOD) [Boo86], RDM [PC86], SD [YC79, SMC74], LCP [War76], and DSSD [Orr77]). We compared our SDM comparisons against other comparisons obtained using other approaches. The results of this comparison demonstrate that process modeling [Ost87, KH88] is valuable as a powerful tool in analysis of software development approaches. Besides, the SDM comparisons result, we obtained through this effort are by themselves valuable for understanding software design activities and SDMs