Integrated aquaculture-agriculture adoption and impact in rainfed farming systems in Sakata, Malawi

ICLARM introduced integrated aquaculture-agriculture (IAA) in Sakata, Malawi three years ago. Since that time, and without extension support, the number of farmers with ponds increased from 4 in 1993/94 to 12 in 1995/96. To learn why and how IAA is spreading, a study of impact and adoption was conducted in the 1995/96 production season. Interviews were conducted with farmers to discuss lAA and collect data on farm function through the use of bioresource flow diagrams. Motivations given by farmers as to why they adopted IAA were to improve household nutrition and income. Constraints to adoption identified by farmers were availability of labor and capital to purchase inputs

Integrated cage-cum-pond culture systems with high valued climbing perch (Anabas testudineus) in cages and low-valued carps in open ponds

An on-farm trial was conducted over 150 days to determine appropriate stocking ratio, growth and production of climbing perch (Anabas testudineus) in cages and carps in open water of ponds in eighteen farmers' ponds from Haluaghat Upazila at Mymensingh district of Bangladesh. One or two 1 m super(3) cage was suspended in each of 12 earthen ponds and other 6 ponds served as control without cages. Climbing perch of 2-3 g in size were stocked in cages while fingerlings of silver carp (Hypophthalmicthys molitrix), catla (Catla catla), rohu (Labeo rohita), mirgal (Cirhinus cirrhosus), rajputi (Puntius sarana) and common carp (Cyprinus carpio) were stocked at 1 fish/m super(2) with a species ratio of 5:4:4:4:2:1 in open water of all ponds to give cage to open-pond fish ratios of 1:1 (T sub(1:1)) and 2:1 (T sub(2:1)) and 0:1 (T sub(0:1)) as three treatments with six replicates each. Survival of climbing perch was higher in T sub(1:1) (61.67%) than that of T sub(2:1) (29.5%) and was significantly different (p>0.05) between the treatments. Stocking of small size climbing perch fry increased the mortality rate in cages. The net yields of Thai koi were 0.13±0.01 (t/ha) and 0.10±0.01 (t/ha) in treatments T sub(1:1) and T sub(2:1), respectively and both were significantly different (p>0.05). Survival of-open-pond carps was high, ranging from 50 to 91.67% with significantly lower in T sub(0:1) than that of T sub(1:1) and T sub(2:1) treatment. Net and gross yield of each carp species were significantly higher in the T sub(1:1) and T sub(2:1) treatment than that in T sub(0:1) treatment. Net revenues were positive but low in all treatments. Therefore, bigger size climbing perch with lower stocking ratio (T sub(1:1)) is suitable for integrated cage-pond culture of climbing perch and carps. However, more on-farm trials in different ecosystem with scientific interventions are necessary to develop the technology for further dissemination among the rural farmers.

Towards the development of an integrated design framework using the Blackboard model

Current research into the process of engineering design is extending the use of computers towards the acquisition, representation and application of design process knowledge in addition to the existing storage and manipulation of product-based models of design objects. This is a difficult task because the design of mechanical systems is a complex, often unpredictable process involving ill-structured problem solving skills and large amounts of knowledge, some which may be of an incomplete and subjective nature. Design problems require the integration of a variety of modes of working such as numerical, graphical, algorithmic or heuristic and demand products through synthesis, analysis and evaluation activities.

This report presents the results of a feasibility study into the blackboard approach and discusses the development of an initial prototype system that will enable an alphanumeric design dialogue between a designer and an expert to be analysed in a formal way, thus providing real-life protocol data on which to base the blackboard message structures.

The role of plants in channel-dyke and field irrigation systems for domestic wastewater treatment in an integrated eco-engineering system

Eight kinds of plants were tested in channel-dyke and field irrigation systems. The removal rates of TP, phosphate, TN, ammonia, CODcr and BOD, in the channel-dyke system with napiergrass (Pennisetum purpurem Schumach, x Pennisetum alopecuroides (L.) Spreng American) were 83.2, 82.3, 76.3, 96.2, 73.5 and 85.8%, respectively. The field irrigation systems with rice I-yuanyou No.1(88-132) (Oryza sativa L.) and rice II- suakoko8 (Oryza glaberrima) had high efficiency for N removal; the removal rate were 84.7 and 84.3%, respectively. The mass balance data revealed that napiergrass, rice I and II were the most important nutrient sinks, assimilating more than 50% of TP and TN. Plant uptake of N and P as percentage of total removal from wastewater correlated with biomass yield of and planting mode. (C) 2000 Elsevier Science B.V. All rights reserved.

A systems view of integrated coastal management

Natural hazards and human activities in the coastal zone are threatening the integrity of the coastal resource system. Conflicts of interest between short term economic benefits and long term ecologic assets should be identified and solved by means of a balanced CZM approach. Systems analysis, supported by mathematical modelling tools are the appropriate instruments to assist the coastal zone manager. The paper presents a general system description of the coastal zone, and focuses on the modelling of the natural subsystem components of this system as a first step towards a model for Integrated Coastal Management (ICM).

An integrated firewall policy validation tool.

Security policies are increasingly being implemented by organisations. Policies are mapped to device configurations to enforce the policies. This is typically performed manually by network administrators. The development and management of these enforcement policies is a difficult and error prone task. This thesis describes the development and evaluation of an off-line firewall policy parser and validation tool. This provides the system administrator with a textual interface and the vendor specific low level languages they trust and are familiar with, but the support of an off-line compiler tool. The tool was created using the Microsoft C#.NET language, and the Microsoft Visual Studio Integrated Development Environment (IDE). This provided an object environment to create a flexible and extensible system, as well as simple Web and Windows prototyping facilities to create GUI front-end applications for testing and evaluation. A CLI was provided with the tool, for more experienced users, but it was also designed to be easily integrated into GUI based applications for non-expert users. The evaluation of the system was performed from a custom built GUI application, which can create test firewall rule sets containing synthetic rules, to supply a variety of experimental conditions, as well as record various performance metrics. The validation tool was created, based around a pragmatic outlook, with regard to the needs of the network administrator. The modularity of the design was important, due to the fast changing nature of the network device languages being processed. An object oriented approach was taken, for maximum changeability and extensibility, and a flexible tool was developed, due to the possible needs of different types users. System administrators desire, low level, CLI-based tools that they can trust, and use easily from scripting languages. Inexperienced users may prefer a more abstract, high level, GUI or Wizard that has an easier to learn process. Built around these ideas, the tool was implemented, and proved to be a usable, and complimentary addition to the many network policy-based systems currently available. The tool has a flexible design and contains comprehensive functionality. As opposed to some of the other tools which perform across multiple vendor languages, but do not implement a deep range of options for any of the languages. It compliments existing systems, such as policy compliance tools, and abstract policy analysis systems. Its validation algorithms were evaluated for both completeness, and performance. The tool was found to correctly process large firewall policies in just a few seconds. A framework for a policy-based management system, with which the tool would integrate, is also proposed. This is based around a vendor independent XML-based repository of device configurations, which could be used to bring together existing policy management and analysis systems.

Integrated spot size converters for InP based photonic systems

The ever increasing demand for broadband communications requires sophisticated devices. Photonic integrated circuits (PICs) are an approach that fulfills those requirements. PICs enable the integration of different optical modules on a single chip. Low loss fiber coupling and simplified packaging are key issues in keeping the price of PICs at a low level. Integrated spot size converters (SSC) offer an opportunity to accomplish this. Design, fabrication and characterization of SSCs based on an asymmetric twin waveguide (ATG) at a wavelength of 1.55 μm are the main elements of this dissertation. It is theoretically and experimentally shown that a passive ATG facilitates a polarization filter mechanism. A reproducible InP process guideline is developed that achieves vertical waveguides with smooth sidewalls. Birefringence and resonant coupling are used in an ATG to enable a polarization filtering and splitting mechanism. For the first time such a filter is experimentally shown. At a wavelength of 1610 nm a power extinction ratio of (1.6 ± 0.2) dB was measured for the TE- polarization in a single approximately 372 μm long TM- pass polarizer. A TE-pass polarizer with a similar length was demonstrated with a TM/TE-power extinction ratio of (0.7 ± 0.2) dB at 1610 nm. The refractive indices of two different InGaAsP compositions, required for a SSC, are measured by the reflection spectroscopy technique. A SSC layout for dielectric-free fabricated compact photodetectors is adjusted to those index values. The development and the results of the final fabrication procedure for the ATG concept are outlined. The etch rate, sidewall roughness and selectivity of a Cl2/CH4/H2 based inductively coupled plasma (ICP) etch are investigated by a design of experiment approach. The passivation effect of CH4 is illustrated for the first time. Conditions are determined for etching smooth and vertical sidewalls up to a depth of 5 μm.

Integrated genetic analysis systems

The overall objective of this thesis is to integrate a number of micro/nanotechnologies into integrated cartridge type systems to implement such biochemical protocols. Instrumentation and systems were developed to interface such cartridge systems: (i) implementing microfluidic handling, (ii) executing thermal control during biochemical protocols and (iii) detection of biomolecules associated with inherited or infectious disease. This system implements biochemical protocols for DNA extraction, amplification and detection. A digital microfluidic chip (ElectroWetting on Dielectric) manipulated droplets of sample and reagent implementing sample preparation protocols. The cartridge system also integrated a planar magnetic microcoil device to generate local magnetic field gradients, manipulating magnetic beads. For hybridisation detection a fluorescence microarray, screening for mutations associated with CFTR gene is printed on a waveguide surface and integrated within the cartridge. A second cartridge system was developed to implement amplification and detection screening for DNA associated with disease-causing pathogens e.g. Escherichia coli. This system incorporates (i) elastomeric pinch valves isolating liquids during biochemical protocols and (ii) a silver nanoparticle microarray for fluorescent signal enhancement, using localized surface plasmon resonance. The microfluidic structures facilitated the sample and reagent to be loaded and moved between chambers with external heaters implementing thermal steps for nucleic acid amplification and detection. In a technique allowing probe DNA to be immobilised within a microfluidic system using (3D) hydrogel structures a prepolymer solution containing probe DNA was formulated and introduced into the microfluidic channel. Photo-polymerisation was undertaken forming 3D hydrogel structures attached to the microfluidic channel surface. The prepolymer material, poly-ethyleneglycol (PEG), was used to form hydrogel structures containing probe DNA. This hydrogel formulation process was fast compared to conventional biomolecule immobilization techniques and was also biocompatible with the immobilised biomolecules, as verified by on-chip hybridisation assays. This process allowed control over hydrogel height growth at the micron scale.