THE EFFECTS OF FLOW MALDISTRIBUTION ON THE THERMAL PERFORMANCE DEGRADATION OF FIN-TUBE HEAT EXCHANGERS

Maldistribution of flow in a heat exchanger has an adverse effect on its thermal and hydraulic performance. Not only does the heat duty reduce but the fluid pressure drop across the exchanger increases too. The characteristics of a maldistribution profile are described by its four statistical moments of probability density function, viz. mean, standard deviation, skew and kurtosis. A novel mathematical analysis technique has been developed to demonstrate the influence of these statistical moments on the heat transfer and pressure drop performance of an exchanger. The analysis has shown that both the mean and standard deviation have the highest degradation effect on the heat exchanger performance while subsequent higher moments have declining effects until the fourth moment kurtosis, which has no significant effect. A discretized numerical method was then used on the fin-tube heat exchanger coil to calculate the magnitudes of thermal degradation as the statistical moments of the air inlet velocity distribution and geometrical parameters of the exchanger are systematically changed. The results show that the degradation is not only dependent on the moments but also on the exchanger NTU, ratio of external to internal heat transfer coefficients, R, and the number of tube rows in the coil. Consequently, new correlation equations have been developed to predict the magnitude of deterioration from a known air velocity maldistribution profile, for a given heat exchanger geometry. An experimental test rig was fabricated to validate the correlation equations. The same experimental data were then used to validate the Computational Fluid Dynamics (CFD) model of the fin-tube heat exchanger. With the same modelling technique, simulations with various exchanger geometry and layout designs can be performed to extract the statistical moments of the maldistribution and predict the heat exchanger performance. By doing so, the design could be optimized to find the lowest possible degradation effects. Maldistribution with low standard deviation and high positive skew is seen to give low thermal performance deteriorations

Buried penis

AbstractBuried penis is a congenital anomaly in which the penis is normal in size but appears to be small (i.e., the external genitalia appear small). This anomaly is usually associated with inadequate outer penile skin, fibrosis of the Dartos fascia, inadequate subcutaneous attachment to Buck's fascia, and narrow opening of the prepuce. Various systems have been used to classify this anomaly and its related conditions. Several symptoms such as difficulty maintaining hygiene and holding the penis during voiding, balanitis, urinary tract infection, and embarrassment when naked have been reported. Adults may present with painful erection, sexual embarrassment, and difficulty with vaginal penetration. Several surgical techniques have been developed to correct this anomaly. Most studies have suggested early surgery. Accurately diagnosing the anomaly and avoiding circumcision are crucial in these patients

Effects of Mowing and Fertilization on Warm Season Turfgrasses

The need to maintain good quality turfgrass at relatively low costs in the face of current energy crisis and inflationary costs have led to the investigations reported in this thesis. A field experiment was conducted to investigate the effect of mowing heights and N fertilization on the commonly cultivated warm season grasses used in the tropics and subtropics. Response trends of zoysiagrass (Zoysia japonica Steud.) and seashore paspalum (Paspalum vaginatum Swartz) were also observed. A greenhouse experiment was conducted to determine the N-K levels required of carpetgrass (Axonopus affinis Chase) which is the main turfgrass used in Singapore for parks and open spaces. The objective of this experiment was to determine the optimum N-K combination required to produce acceptable turf at lowest input. Three nitrogen fertilizer levels and two mowing heights were used in the field experim.ent. N levels were recommended low, medium, and high for the individual turf species. Growth parameters used for evaluation of responses were visual ratings, clipping dry weights, and chlorophyll contents in both experiments. In addition, root depths were measured for the field experiment and dried shoots and roots were weighed at the termination of the glasshouse pot culture experiment. Tissue N analysis was carried out to relate the growth responses observed. Mowing heights affected visual ratings of all turf species. However, they differ in response to mowing height in that bermudagrass (Cynodon dactylon (L.) Pers.) and centipedegrass (Eremochloa ophiuroides (Munro.) Hack.) had higher visual ratings at low mowing height whilst carpetgrass (Axonopus affinis Chase) and St. Augustinegrass (Stenotaphrum secundatum (Walt.) Kuntze) had higher visual ratings at high mowing heights. Mowing heights had different effects on different grasses in terms of clipping dry weights. The method of collecting clippings was less than desirable and led to higher experimental error for some grasses than others. Chlorophyll contents followed the same trend as visual ratings in that bermudagrass and centipedegrass had higher chlorophyll content at low mowing heights whilst centipedegrass and St. Augustinegrass were higher at high mowing heights. Root depths of St. Augustinegrass decreased significantly at low mowing height. The root depths of all other species tended to decrease with closer mowing although the effect was not significant at the 5% level. Centipedegrass was the only species that responded to N fertilizer as expected. Clipping dry weights, chlorophyll contents, and %N increased with increasing levels of N. Rooth depth decreased as N level increased. The reason for lack of response of other species to N fertilizer was probably due to insufficient differences in N levels applied. In the glasshouse experiment, increasing N levels from 6.25 ppm to 50 ppm, increased visual ratings, clipping dry weights, and chlorophyll contents, and depressed root growth. N has no effect on shoot dry weights at termination of the experiment. Average results over the experimental period showed that K had no effect on visual ratings, shoot dry weights, and root dry weights. The optimum level for K for maximum chlorophyll content was 15 ppm whereas clipping dry weights increased with increasing K above 15 ppm. Combinations within the range of 25 ppm N with 15 ppm K and 25 ppm N with 30 ppm K produced good quality carpetgrass without being over luxuriant. However, as this was based on data collected from a glasshouse experiment, it should be further tested in the field. Visual ratings was found to be a reliable parameter for evaluation of turfgrass quality, and should suffice for routine purposes. Visual ratings were correlated with clipping dry weights, chlorophyll contents, and root dry weights

Congestion Management of a Deregulated Power System Using Fuzzy Logic

Regulated Power System is widely accepted and practised in several countries. The entire electric utility of this traditional system is entirely owned and managed by one organization or commonly the government. The dictation right, monopoly concept and with no third party to ensure the efficiency of the management had caused this structure of industry become less competitive and less efficient. When this problem arises, the solution is not a better set of rules, but a structural change. With the ongoing liberalization of electricity markets, it is now moving towards the era of Deregulated Power System. This is a type of restructuring in Power Industry. The general mechanism of deregulation is to unbundle the Generation, Transmission and Distribution into generating companies (GENCOs), transmission companies (TRANSCOs) and distribution companies (DISTCOs). This unbundled system is very competitive as multiple GENCOs would compete among themselves to supply DISTCOs electric utility through short or long term contracts while the consumers are free to select any GENCOs that provide them with the best service and best price. Therefore, deregulation will be the future of realizing sustainable development at high efficiency. However, in open access environment where the consumers and distributors are free to choose their own generation supplier, transmission congestion is a major concern of this unbundled system. Transmission congestion is the condition where power that flows across transmission lines and transformers exceeds the physical limits of those lines. The main reasons for congestion management are due to the increase demand of electricity usage, the construction of transmission is expensive and the pressure from environmental groups that restrict construction of transmission. The chances of transmission lines getting over-loaded is comparatively higher under deregulated operation because vary parts of the system are owned by different companies and under varying service charges. Several conventional methods were used to manage congestion in transmission line. These methods are Linear Programming Method, Newton-Raphson Method, Quadratic Programming Method, Nonlinear Programming Method and Interior Point Method. The disadvantages of these conventional methods are complex mathematical formulation, unable to solve real-world large-scale power system problems, poor convergence and the system is slow when the variables are large. In recent years, Artificial Intelligence Method is frequently used as it can solve highly complex problems. Fuzzy Logic is one of the types under this Artificial Intelligence Method. Hence, in this paper, Fuzzy Logic approach is implemented for congestion management. This approach deals with approximation rather than precision. The simple rule-based of Fuzzy Logic is using “IF X AND Y THEN Z”. The load flow of the transmission line will be used to model Fuzzy Logic in controlling transmission congestion and tested using IEEE Reliability Test System-1996 (RTS-96). The results showed the congestion level for Weekly Load and Daily Load using the data in IEEE RTS-96. With the congestion level, the price can be further determined by the distributor according to Zonal Pricing Method and Nodal Pricing Method

Theatre as an Individual and Collective Art

Art can be as tangible as objects. Art can also be as intangible as ideas. Art exists in multiple forms, such as painting, music, literatures, dancing, acting, and so on, which at the same time defines the form of theatre art. The multi-dimensional nature of theatre art is complex and requires a lot from people, including time, money, and effort. Such effort is not singular but rather diverse and multi-layered. It not only requires people to have contributive skills but also the ability to bind together the skills that different people have. Theatre is collaborative by nature, so communication is key. When people’s attention is drawn to the performance itself, the communication work behind the curtain is often left overlooked, which results in a lack of acknowledgement of people’s commitment and contribution and a lack of opportunity for improvement. Therefore, this project aims to illuminate the leadership and internal communication in a team, accompanied by a podcast episode “From Vision To Practice: A Conversation with Wendy-Marie.” Following Chapter One: Leadership and Internal Communication, which examines and evaluates group communication from a leadership and internal communication perspective, is Chapter Two: Practical Component describing the production of a podcast episode, and Chapter Three: Reflections and Artistic Analysis which recounts my artistic journey and my growth at Hollins University as a double major in Communication Studies and Theatre

Women in American Pop Music: Christina Aguilera’s impact on cultural narratives

Pop music as a mainstream medium is often more enjoyed than critically studied. Former studies and literatures point out a major issue that many American female pop music artists face. These artists are often confined in a box that reduces their full human-being attributes to a narrowed view, where their identity is portrayed in a diminishing and inaccurate way. Despite this narrowed narrative of what a woman should be, this box has become a norm that many female artists must adhere to in order to achieve mainstream success. This paper responds to this phenomenon by analyzing Christina Aguilera’s music, spanning from 1999 to 2018, to understand the cultural narratives of her music in response to the findings in literature. This paper argues that Aguilera’s music explores multi-dimensional aspects of life and womanhood, challenging the limited portrayal of women in the mainstream music industry. With a focus on lyrics, this paper identifies five themes and examines the cultural relevance of these themes in her music, including (1) romance and love, (2) introspection of vulnerability, (3) gratitude for support, (4) empowerment, and (5) sexual liberation. These themes are culturally relevant in a way that they challenge and reach beyond the dominant narrative of womanhood, by offering a view that captures women’s multi-dimensional identities and experiences

The application of facilities management to hotel renovations in Hong Kong

Thesis (B.Sc)--University of Hong Kong, 2004.published_or_final_versio

Quenched chiral logarithms in lattice QCD with overlap Dirac quarks

We examine quenched chiral logarithms in lattice QCD with overlap Dirac quarks. From our data of m_pi^2, we determine the coefficient of quenched chiral logarithm delta = 0.203(14), 0.176(17), 0.193(17) and 0.200(13) for lattices of sizes 8^3 times 24, 10^3 times 24, 12^3 times 24 and 16^3 times 32 respectively. Also, for the first three lattice sizes, we measure the index susceptibility of the overlap Dirac operator, and use the exact relation between the index susceptibility and the eta' mass in quenched chiral perturbation theory to obtain an independent determination of delta = 0.198(27), 0.173(24), 0.169(22), which are in good agreement with those determined from m_pi^2.Comment: Lattice2002(chiral), 3 pages, 2 figure

Board Structure, Board Process and Board Performance: A Review & Research Agenda

While the conceptual importance of boards of directors in modern day businesses is undisputed, it is equally crucial to study the relationship between board of directors and board performance. The objective of this study is to examine the current literature and suggest that a better way to examine the role of board of directors is through a careful study on board structure, board processes and board performance, instead of focusing on board structure and firm performance alone

Establishment Of An Agrobacterium-Mediated Transformation System And In Vitro Regeneration Protocol For Rice (Oryza Sativa Sp. Indica Var.) Mr219

This study consisted of several parts which include development of tissue culture and regeneration system for local indica rice MR 219 variety, establishment of Agrobacterium-mediated transformation system and molecular analysis to confirm introduction of oil palm leaf-specific promoter in putative rice transformants Different concentrations of 2-4,D (0, 1.5, 3.0, 4.5, 7.5 and 10mg/l) were tested for embryogenic and nodular calli induction from scutellum region of indica rice using MS medium supplemented with 500 mg/L proline, 500 mg/L casein hydrolysate, 30 g/L sucrose and 2.5 g/L gelrite and it was shown that 3.0mg/l 2-4,D was the best concentration to use.Different concentrations of 6-benzylaminopurine (BAP) (1.0, 2.0, 4.0, 6.0 mg/l) alone or in combination with 0.5mg/l naphthalene acetic acid (NAA) and two different concentrations of Kinetin (1.0 and 2.0 mg/l) in MS media in the presence of 500 mg/L proline, 500 mg/L casein hydrolysate, 30 g/L sucrose and 6.0 g/L gelrite were used to determine the most suitable plant growth regulators for regeneration of rice plants. The results showed that BAP 6.0 mg/l alone is the best condition for multiple shoot formation from desiccated rice calli. Plasmid pCAMBIA 1301 is a binary vector having hygromycin resistant gene (hpt) as selectable marker gene in the T-DNA region. The minimal inhibitory concentration of hygromycin was determined by testing different concentrations of hygromycin ( 10, 20, 30, 50, 70 ,90mg/l) for survival of rice embryogenic callus. Hygromycin at 50 mg/l which gave 53.34% retarded growth of calli but with minimal browning was chosen as the most suitable for selection of putative transformants. This experiment together with the other tissue culture experiments were conducted and arranged in a Completely Randomized Design (CRD). The oil palm leaf-specific gene promoter was cloned individually into binary vector pCambia 1301 carrying β-glucuronidase (GUS) reporter gene after removal of the CaMV 35S promoter and the recombinant plasmids produced were transferred into Agrobacterium tumefaciens strain EHA105 and C58.Agrobacterium tumefaciens strain EHA 105 and C58 shown to contain oil palm leaf-specific promoter based on PCR analysis were used to transform rice calli. Calli subjected to heat and centrifugation treatments were found to be suscessfuly transformed based on GUS histochemical analysis. Different concentrations of antibiotics on the MS medium including carbenicilin (250, 500, 800, 1000, 1500, 1800 and 2000 mg/l), cefotaxime (250, 500, 800 mg/l), timentin (200,300 mg/l) either alone or in combination were not successful in eliminating Agrobacterium after transformation. PPM (plant preservative mixture) was found to be the best chemical to remove excessive Agroabcterium. Calli were subsequently transferred to regeneration medium (MS salts gelled with 500 mg/L proline, 500 mg/L casein hydrolysate, 30 g/L sucrose and 6 g/L gelrite, 50mg/l hygromycin B, pH 5.8) after hygromycin selection. Successful introduction of the oil palm tissue-specific promoters in putative transformants were confirmed via PCR and real time PCR analysis using primers designed based on the oil palm leaf-specific promoter sequence. Real time PCR analysis showed that the gene copy numbers of transgenic calli were not more than 2 copies per genome. Using GUS histochemical assay it was shown that CAMV 35S promoter but not the oil palm leaf-specific promoter can drive GUS expression in transformed rice calli