Faculty of Engineering and Built Environment

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Adapt or Die! Building Information Modelling (BIM)
(Association of Schools of Construction of Southern Africa, 2016) Haupt, Theo C.; Hefer, Elke
Purpose: The emergence of Building Information Modelling (BIM) demands that quantity surveyors review their roles in the construction sector. This study examines the responsiveness of the quantity surveying discipline to BIM. Design/methodology/approach: A sample of quantity surveyors in Durban will be surveyed using an instrument developed from published literature on responses of quantity surveying to BIM. Research limitations: The sample of quantity surveyors was drawn from the Durban area using the Association of South African Quantity Surveyors (ASAQS) and South African Council for the Quantity Surveying Professions (SACQSP) database. Findings: Preliminary findings suggest that quantity surveyors’ knowledge about BIM, software and innovation was at best rather average. They recognized the most obvious benefits of embracing BIM such as the time taken to produce Bills of Quantities and accurate cost estimation. Largely because of their lack of knowledge of available technologies they could not comment assertively on many of the issues surrounding the relationship between BIM and quantity surveying. This further resonates with the uncertainty that exists surrounding BIM and its business value and return on investment. They disagreed that technological advancements presented threats to their existence or the services that they traditionally offered. In the main the findings of the study resonated with those of other studies done particular in developing countries. Response to conference theme: This study identifies the reasons why BIM is not being readily embraced by quantity surveyors more pervasively. Practical implications: The findings provide the opportunity to improve the services currently offered by quantity surveyors but also new and innovative services driven by BIM
Airborne antenna systems for DVB-RCS solutions
(IEEE, 2016) Ilcev, Stojce Dimov
This paper introduces development and implementation of new Airborne Satellite Antenna (ASA) used for Very Small Aperture Terminal (VSAT) of Aeronautical Satellite Broadband System (ASBS) known as a Digital Video Broadcasting-Return Channel via Satellite (DVB-RCS). Directional High Gain Antenna (HGA) of ASA system usually needs to be protected by special radome and always positioned in the focus of satellite by a special antenna mechanical and electrical antenna tracking mechanism situated on the special stabilized pedestal. The several possible types of broadband ASA via different Radio Frequency (RF) band, such as Ku-band transceiving, airborne satellite broadband antenna, L and Ku-band antennas for DVB-RCS and Internet Protocol Television (IPTV) solutions, Ka-band transceiving antenna system for DVB-RCS solutions, Antenna Systems for Aeronautical Satellite Broadcasting (ASB) are discussed.
Airborne satellite antenna steering and mounting systems
(IEEE, 2016) Ilcev, Stojce Dimov
This paper describes the steering and mount systems of Airborne Satellite Antenna (ASA) as a most important and sensitive part of both Aeronautical Mobile Satellite Communication (AMSA) and Aeronautical Mobile Satellite Broadcasting (AMSB) systems. In general, most of ASA solutions are small and easy to install onboard aircraft such as Low Gain Antenna (LGA). However, in particular, some of ASA systems are quite complex, relatively large and heavy, especially airborne High Gain Antenna (HGA) for Aircraft Earth Stations (AES), such as Inmarsat-H, High Speed Data (HSD), Swift64, SwiftBroadband and Digital Video Broadcasting-Return Channel via Satellite (DVB-RCS) antennas, so they need sophisticated steering and mounting systems. Over the past decade are developed the steering ASA broadband system, which main components are reduced considerably in both physical size and weight. These reductions are presented in this research that brings greater Effective Isotropic Radiated Power (EIRP) from satellite transponders coupled with GaAs-FET technology at the front end the satellite receiver. In this paper are also introduced existing types of mechanical, electrical, combined and other mount systems of ASA steering system. The ASA has to be always pointed towards the satellite in spite of aircraft motions. At this point, the mount airborne satellite system as one of the main requirements in designing the mobile satellite antenna systems from the technical and rational viewpoints is discussed.
Airborne satellite navigation and other integrated antenna systems
(IEEE, 2016) Ilcev, Stojce Dimov
This paper is introducing the airborne satellite navigation and other integrated antenna systems for both weather and special navigation systems. In general, most of navigation antennas are omnidirectional, small and easy to install onboard aircraft, such as Global Navigation Satellite Antennas (GNSA) and other integrated antenna systems. However, in particular, some new developments of navigation antennas are providing miniaturized Global Navigation Satellite System (GNSS) antenna array technologies that significantly reduce the size of the antenna elements and the array dimensions. The passive and active GNSA for mobile applications including aeronautical are presented, which include all existing types of GNSS solutions. The GNSS antennas are usually omnidirectional, so they don’t need to be always pointed towards the satellite in spite of aircraft motions. In this paper are presented commercial aspects of the aircraft GNSS antenna technologies, their importance and integration with a digital beam-steering antenna electronics package. In addition, the solutions of different cost effective integrated antenna systems with GNSS antennas, such as airborne WAAS, XM, Weather, Sirius, ISL, DME, ADF, VOR, LOC, GS and other antenna systems are discussed.
The appropriate material specifications and manual are key for effective gravel roads design, construction and maintenance practice
(Eastern Seaboard Intermodal Transportation Applications Center, 2012-10) Mwaipungu, Richard R.; Allopi, Dhiren
It is a matter of fact that the gravel road network dominates as the mode of transport infrastructure in most of sub-Sahara Africa. These roads comprise a huge national asset that requires adherence to appropriate locally formulated Pavements and Materials Design Manual (PMDM) and Standard Specification for Road Works (SSRWs) in order for them to give satisfactory performance during their design life. As the length of the engineered gravel road network is steadily growing in Tanzania and elsewhere in sub-Sahara Africa, appropriate PMDM and SSRWs to be employed during design, construction and upkeep of this investment becomes increasingly important for optimal use of locally available gravel materials. In response to the above call, a number of sub-Sahara Africa countries, Tanzania included, has in place PMDM and SSRWs, which are being used during the design and construction of new gravel roads and also during maintenance and rehabilitation of existing gravel roads. These PMDM and SSRWs are used in order not only to standardize design practices and quality control during the design, construction and maintenance period, but also to be able to predict the performance of gravel roads. For these PMDM and SSRWs to be effective and dynamic they have to address local condition and after a certain period of time are to be revised so as to capture changes which are constantly occurring in the gravel road construction industry. The intention is that eventually it should be obligatory to observe the PMDM and SSRWs during design, construction, and maintenance of gravel roads, as they will carry with them the practical experience of over extensive period of time to be questionable. Although it’s always mentioned that engineering practice and judgment have to be observed during the use of any PMDM and SSRWs and under no circumstances shall the PMDM and SSRWs waive professional judgment in applied engineering, it has to be acknowledged that PMDM and SSRWs carry with them some authority in arriving at a final decision during the initial stage of design, preparation of tender documents and whenever an inexperienced engineer is supervising part of the project or a new challenge emerges during the execution of road works. This paper focuses on what is specified in Tanzania PMDM and SSRWs, in particular on gravel roads materials, design, construction and maintenance in one part and what is practiced in the country in another part as it influences the performance of gravel wearing course. It also compares these PMDM and SSRWs with those of developed countries and South Africa. It is expected that by addressing those areas the PMDM and SSRWs have fallen short will make them effective tools in gravel roads design, construction and maintenance works.
A cluster network based distributed resource management scheme for OBS networks
(IEEE, 2016-11) Pule, Beverley; Nleya, Bakhe; Mutsvangwa, Andrew
All-optical networks (AON) based on optical burst switching (OBS) are rapidly becoming the ultimate backbone network solution for next (future) generation networks because of their potential ultra high bandwidth capacities both at transmission and switching levels. The OBS switching paradigm was conceptualized and ultimately designed using the good features of both optical circuit switching (OCS ) and optical packet switching (OPS) and thus provides improvements over wavelength routing in terms of bandwidth efficiency, at the same time eliminating the need for huge buffers at the network edges as well as optical –to- electronic conversions and vice-versa of the data bursts at the core (switching) nodes. With such networks end to end light channels will transmit users data , transparently i.e. without being aware of its bit rate, modulation format as well as network protocol thus enhancing capacity, flexibility and scalability of the network. A buffer less /limited buffered lead OBS network would mean high contention and blocking, hence to guarantee and end-to-end consistent QoS in would require that the resources are properly managed. Effective management of both control and data planes is a key issue in this regard. Thus in this paper, we propose and analyse a partial distributed resource management scheme for OBS networks. We describe the concept, followed by routing and wavelength selection procedures.
Conceptual framework of environmental sustainable interventions with the use of green infrastructure design criteria on projects
(2014) Saroop, Shian Hemraj; Allopi, Dhiren
This paper presents a conceptual framework that incorporates eco-efficiency on Infrastructure projects with the use of the environmentally sustainable criteria on infrastructure projects. Mainstreaming environmental aspects and incorporating the eco-efficiency concept into various stages of infrastructure development have not been considered as much as they should have been. Engineers need to look at greener technologies rather than just using traditional engineering solutions. This paper aims to develop a framework that enables a project to be designed in accordance with environmentally sustainable criteria. The key aim of the framework was to create a more socially, economically, and environmentally sustainable neighbourhood, which focused on combating flooding, waste management, water recycling and enhancing biodiversity.
Control of multi-level voltage source converters integrating a wind turbine system into the grid
(IEEE, 2016) Hamatwi, E.; Davidson, Innocent E.; Gitau, M.N.
In recent years, wind energy has proven to be the most competitive and environmental friendliest renewable energy (RE) source for generating electricity. Wind farms are more likely to be located far from the load centres, and hence the generated power has to be transmitted over long distances. A high voltage direct current (HVDC) transmission system increases the transmission capacity, improves the system stability, and possesses lower transmission losses. Therefore, it is the preferred means for power delivery over long distances compared to the high voltage alternating current transmission system. In this paper, a 690V, 2MW wind turbine is modelled to be integrated into a 33kV AC grid via a 3-level Neutral-Point-Clamped Voltage Source Converter-based HVDC transmission system. Three control schemes were implemented: a pitch-angle controller, a controller applied to the generator-side converter, and a controller applied to the grid-side converter. The proposed wind energy conversion system and control schemes were implemented in MATLAB/SIMULINK and simulations were carried out to analyse the performance of the system.
Creating eco efficient township infrastructure projects with the use of green engineering solutions and sustainability criteria
(Institute of Municipal Enginering of South Africa, 2015) Saroop, Shian Hemraj; Allopi, Dhiren
Globally, the construction industry is one of the main contributors to the depletion of natural resources and a major cause of unwanted side effects such as air and water pollution, solid waste, deforestation, health hazards, global warming, and other negative consequences (Harvey and Wayne, 20084). As we face significant planetary issues such as global warming, it is clear that the engineering profession has a significant part to play in affecting the future of our planet. In order to stay competitive and to meet upcoming stricter environmental regulations and customer requirements, designers have a key role in designing civil infrastructure so that it is environmentally sustainable. These and other factors have compelled the engineer to design with greater care and in more detail. The changing roles of engineers will be highlighted, in order to react to changes in climate. Mainstreaming environmental aspects and incorporating the eco-efficiency concept into various stages of infrastructure development have not been considered as much as they should have been. Engineers need to look at greener technologies rather than just using traditional engineering solutions. This paper looks at the effects of climate change on infrastructure and the changing role of engineers. It aims to demonstrate the use of sustainability criteria on infrastructure projects. The use of the proposed criteria would ensure a sustainable design for township infrastructure services through the consideration of scare resources, ecological sensitivity in the design and planning of infrastructure projects. This paper focuses on the concept of eco-efficiency in infrastructure design that promotes the use of the greener engineering options, enabling him/her to choose the one likely to yield the best performance with the least environmental impact. It looks at a number of recommended green practices on infrastructure services design, that are environmentally sound placing, fewer burdens on the environment.
Data re-sequencing in Smart Grids
(IEEE, 2016-11) Khumalo, Zephaniah Philani; Nleya, Bahke
Currently, legacy electrical power grids are being modernized into Smart Grids. These will in turn play a crucial role in real-time balancing between energy productions versus energy consumption. Each Smart Grids will dedicate an advanced metering infrastructure that facilitates collection, storing as well as analyzing data from smart meters to the authorized parties, and also carrying commands, requests, messages and software updates from the authorized parties to the smart meters. As such, data aggregation as well as unimpeded data relaying is a prerequisite for guaranteeing a large acceptance and deployment of Smart Grids. In this paper we provide an overview framework for analyzing packet re-sequencing within the Smart Grid. We utilize the random shortest path calculation algorithm to select the desired routes from source to a given destination. It is from among these that ultimately multipath (dual path) routing of the Advanced Metering Infrastructure data is carried out, hence resulting in re-sequencing necessities.
Evaluation of end-to-end latency for segmented bursts in OBS networks
(IEEE, 2016) Mutsvangwa, Andrew; Nleya, Bahke; Gomba, Ndadzibaya Masimba; Ngeama, Ndunga
In Optical Burst Switched (OBS) networks several contention resolution schemes such as wavelength conversion, fibre delay lines (FDLs), deflection routing and burst segmentation have been proposed. To provide the differential quality of service (QoS) for different classes of packets, priority-based segmented burst assembling at the edge nodes coupled with segment level transmission in the core nodes (in the event of congestion or contention) is proposed. All packets are assembled in units called segments according to two priorities, high priority (HP) and low priority (LP). HP segments are always placed at the head end of the composite burst as they are more delay sensitive, whereas the LP segments fill up at the tail end. Only in the event or anticipation of contention/ congestion occurrence, the affected section(s) of the network switch to segment transmission mode in which the composite burst is from this point decomposed into its individual segments and streamed (segment level transmission) along the same route to the destination end. The limited buffering in the core nodes will facilitate temporary buffering of the contending segments as since they are relatively smaller. The queuing at the inputs may lead to differential delays in the core nodes due to possible addition of segments from other links. This ultimately affects the inter-segment-gap between successive data segments ferrying packets of the same source thus leading to increased jittery whose magnitude may compromise the desirable QoS. In this paper we analyze inter-segment delay variations as a function of the number of nodes traversed.
Exploring industry's contribution to the labour-intensive construction of low order rural community access roads
(2020) Jairam, Santosh; Allopi, Dhiren
The Government of South Africa supports labour-intensive work methodologies as a means of alleviating unemployment in South Africa. In 2004 the Expanded Public Works Programme (EPWP) was formed to promote labour-intensive work methods due to the high unemployment situation. The EPWP is a nationwide programme using public funds to encourage employment by using labour-intensive work methodologies with the intention of reducing national poverty. The programme covers four sectors. The four sectors are environment and culture, infrastructure, social and non-state. The largest component is infrastructure; roads being part of the infrastructure component provides the highest potential for employment creation. Both international and local experience has revealed that by having trained supervisory staff and a proper employment framework, labour-intensive work methods can be successfully used for projects such as roads, sidewalks, storm water drains, trenches, buildings, sanitation and water. The national government, based on this experience and due to high levels of unemployment, has encouraged the use of these type of infrastructure projects as a way of contributing to the alleviation of unemployment. “Only twelve per cent of the road sector budget is used for labour-intensive projects” (Public Works 2012b: 1). This implies that there have been no drastic changes in the extent to which labour-intensive work methodologies have been used in the road works programme. This study focused on exploring parastatals’, consultants’ and contractors’ contribution to the labour-intensive construction of low order rural community access roads in the Outer West region of eThekwini’s Municipality, KwaZulu-Natal, in accordance with the EPWP Guidelines. The population consisted of 101 individuals from the contracting, consulting and parastatal fields of employment who had worked on EPWP related labour-intensive road projects in this region. All 101 individuals were chosen as the sample size A qualitative and quantitative approach was used in this research to gather data on the contribution made by the civil engineering industry to the promotion of labourintensive road construction methods. This approach allowed for an understanding of the motivation and the experiences of consultants, contractors and parastatals regarding the design and construction management choices they have made. Data was collected via a questionnaire containing open-ended questions and rating scales from 87 civil engineering staff that were employed by parastatals, contractors and consultants who were involved in designing, constructing and managing labourintensive construction of low order rural community access roads in the Outer West region of eThekwini Municipality. In addition, interviews were conducted with same 87 civil engineering staff that were involved in designing, constructing and managing these labour-intensive road construction projects during the period from 2015 to 2019. Data collected overwhelmingly suggested that very little practically is being done to promote labour-intensive construction of low order community access roads. The nature of engagement that does occur is largely through the filling in of basic reporting forms and providing basic small scale informal training and work to labour. No standard specification document is in place to enforce labour-intensive construction of rural community access roads. The documents that are in place merely serve as guidelines and administrative data collection tools rather than helping to promote labour-intensive road construction.
Guiding principles for grid code compliance of large utility scale renewable power plant intergration onto South Africa's transmission/distribution networks
(IEEE, 2016-11) Sewchurran, Sanjeeth; Davidson, Innocent E.
Renewable energy generation technologies with its short lead times have become an attractive alternative to assist South Africa to solve its energy crisis and hence led to the Government calling upon Independent Power Producer to enter the market. Subsequently, the Integrated Resource Plan 2010 set a target of 17 800 MW (equivalent to 42%) of new electricity generation capacity in the country to be derived from renewable energy sources. The South African Renewable Energy Grid Code was then published in 2010 to assist with safe and technical integration of these plants into the South African grid. Electricity utilities are now faced with the task to understand the code and carry out testing of these renewable power plants in order to certify them grid code compliant. This paper assists by discussing the requirements of the South African Renewable Energy Grid Code Version 2.8 with testing methods to check grid code compliance.
Implementation of orbit constellations for Satellite Distress and Safety Systems (SDSS) of Cospas-Sarsat network
(IEEE, 2016) Ilcev, Stojce Dimov
In this paper is described implementation of different orbit constellation, such as Polar Earth Orbits (PEO), Medium Earth Orbit (MEO) and Geostationary Earth Orbit (GEO) in function of the Satellite Distress and Safety Systems (SDSS) of Cospas-Sarsat networks for all mobile applications. The panel of International Maritime Organization (IMO) together with Inmarsat mobile satellite operator provided technical and economical studies regarding the extension of the GEO satellite system and to cover Polar Regions. This initiative was performed by international Cospas-Sarsat in designing LEO-polar constellation for full Earth coverage. Some important features of a constellation are introduced such as type of polar and other satellites orbits needed for continues coverage in function of combined distress and safety communication solutions for all Mobile Earth Stations (MES) at sea, on the ground and in the air.
Influence of effluent type on the performance of chitosan as a coagulant
(Akshar Publications, 2014) Pambi, Ritha-Lorette Luti; Musonge, Paul
The use of chitosan as a bio-polymeric coagulant has continued to attract interest in water treatment due to its biodegradability and non-toxicity. Its ability to treat effluents of high organic content has been investigated in some food processing industries. The focus of the present study is to compare results of the use of chitosan in the treatment of effluent from a Sugar Processing Plant (SPP), with those obtained from the treatment of wastewater from a Milk Processing Plant (MPP) and from a Brewery Processing Plant (BPP), in order to determine the influence of effluent type on the impurities removal efficiency. The treatment of the MPP provided the best removal efficiency (99% suspended solids removal and 70% COD removal) in comparison to the SPP (98% suspended solids removal and 11% COD removal) and BPP (95% suspended solids removal and 50% COD removal). The optimum pH value varied as a function of the type of effluent with BPP= 4.5, SPP = 4.5 and MPP =7. The results indicate that chitosan is not very efficient for the removal of dissolved matter. A relationship between total suspended solids (TSS) and total dissolved solids (TDS) has been developed.
A review of LCC-HVDC and VSC-HVDC technologies and applications
(IEEE, 2016) Oni, Oluwafemi E.; Davidson, Innocent E.; Mbangula, Kamati N.I.
High Voltage Direct Current (HVDC) systems has been an alternative method of transmitting electric power from one location to another with some inherent advantages over AC transmission systems. The efficiency and rated power carrying capacity of direct current transmission lines highly depends on the converter used in transforming the current from one form to another (AC to DC and vice versa). A well configured converter reduces harmonics, increases power transfer capabilities, and reliability in that it offers high tolerance to fault along the line. Different HVDC converter topologies have been proposed, built and utilised all over the world. The two dominant types are the line commutated converter LCC and the voltage source converter VSC. This review paper evaluates these two types of converters, their operational characteristics, power rating capability, control capability and losses. The balance of the paper addresses their applications, advantages, limitations and latest developments with these technologies.
Review on the lime-soil stabilization as one of the successful technologies used in the improvement of road-soil-pavement layers strength
(Southern African Transport Conference, 2016) Bhengu, P.H.; Allopi, Dhiren
In general terms, transport infrastructure by definition describes the framework that supports our transport system. This includes, railways, sea-ports, airports and, in particular road pavements. In South Africa, the South African National Roads Agency’s (SANRAL) prime mandate is to finance, improve, manage and maintain the national road networks, with other roads maintained and managed by provincial or local authorities. But due to increasing traffic and heavy-duty transport loads in many parts of the country, road pavement layers are having difficulty in coping with increasingly heavy tonnages and most now exhibit damage in their lower layers. It is for this reason that the engineering properties of soil layers underneath the pavement surfaces need to be improved using a variety of techniques. One such technique entails the improvement of soil strength through chemical stabilisation through the use of lime as the stabilising agent. The term lime soil stabilisation applies primarily when lime is introduced to soil that is reactive to create strength development in the long run through pozzolanic reaction. In South Africa, lime is utilised extensively in the construction of roads. In this paper, a review on literature based on the practices of lime soil stabilisation with the object of improving the engineering properties of soil is presented, with emphasis on the production of lime, nature of soils suitable for lime-soil stabilisation, the behaviour of lime-stabilised materials and the chemistry related to lime-soil stabilisation.
Satellite look angles, track and geometry in Mobile Satellite Communications
(IEEE, 2016) Ilcev, Stojce Dimov
This paper describes Satellite Look Angles, Track and Geometry in the Space and their significance with regard to the spacecraft use for Mobile Satellite Communications (MSC) systems. Basic geometric theory of satellite coordinates is applied to determine the geographical azimuth and elevation (spacecraft altitude) angles required to point mobile satellite tracking antenna to the Geostationary Earth Orbit (GEO) or Non-GEO communication satellites. The mathematical treatment introduced in this paper takes into consideration circular and elliptical orbits. During more than three decades, commercial MSC networks have utilized GEO satellites extensively to the point where orbital portions have become crowded; coordination between satellites is becoming constrained and could never solve the problem of polar coverage. However, other Non-GEO MSC solutions have recently grown in importance because of their orbit characteristics and coverage capabilities in high latitudes and Polar Regions. The important parameters of the Satellite Look Angles such as Elevation and Azimuth angles and Satellite Track and Geometry such as Longitude and Latitude values are described.
A secured access control architecture consideration for PLC based smart grids
(SATNAC, 2015) Mooketsio, Thsepiso; Nleya, Bakhe; Dewa, Mendon; Mutsvangwa, Andrew
Abstract—Power supply, distribution and generation industry is now turning the existing electrical grids to smart grids, thus making them more efficient in both effective power management and reliability, reduced production costs, and more environmen-tally friendly energy generation. Despite its attractive features, Smart Grid technology remains vulnerable to security threats. This paper summaries some of these potential security issues by exploring a data access control mechanism that ensures privacy to customers. The proposed access control mechanism gives selec-tive access to consumer data stored in data repositories and used by different smart grid users. A n attribute-based encryption (ABE) is suggested. The entire grid network is subdivided into clusters each with its own remote terminal unit (RTU) as well as a gateway smart meter. User data in a given cluster is aggregated and sent to the local substation where it is monitored by the RTU. RTUs and users have attributes and cryptographic keys dis-tributed by several key distribution centers (KDC). RTUs send data encrypted under a set of attributes. Users can decrypt infor-mation provided they have valid attributes. The access control scheme is quite resilient because of its b e i n g distributed in na-ture and does not rely on a single KDC to distribute keys. The encryption algorithm is based on Diffie-Hellman key establish-ment protocol and hash-based message authentication code, which allows smart meters at different clusters of the smart grid to mu-tually authenticate prior to data/information exchange and in the process maintaining low latency as well as relatively fewer au-thentication associated messages . Overall the control scheme is relatively collusion resistant.
A smart grid based algorithm for improving energy efficiency of large scale cooperating distributed systems
(IEEE, 2016) Nleya, Bakhe; Mutsvangwa, Andrew; Dewa, Mendon
A smart grid (SG) is a sophisticatedly integrated hybrid power generating system which allows bidirectional energy as well as management data exchanges. In this paper we look at improving energy efficiency in large scale cooperating power consuming as well as power generating systems. We discuss a clustered as well as hierarchical power scheduling algorithms that are geared towards optimizing the management of power tariffs, storage and distribution in a cooperative environment. From a generation perspective, solar intensity prediction is proposed for power generation forecasting and whereas from a power consumption perspective, we evaluate and model the power consumed by these distributed systems (consumers) and propose improving resource allocation, scheduling and network traffic management so as to make network and computing resources more power efficient.