Добірка наукової літератури з теми "Specific fuel consumption"

Pure vegetable oils have the greatest promise for alternative fuels for internal combustion engines beside the depletion of conventional petroleum resources. Among various possible options, pure vegetable oils present promising of greener air substitutes for fossil fuels. Pure vegetable oils, due to the agricultural origin, liquidity, ready availability, renewability, biodegradability are able to reduce the CO2 emissions in the atmosphere. Also, in Vietnam, pure vegetable oils such as soybean oil (SoO100), coconut oil (CO100) and sunflower oil (SuO100) are available. The paper presents the results of using heated pure vegetable oils for diesel engine D243 with power of 80 hp (58.88) kW. The results of determining the power (Ne), specific fuel consumption (SFC) and efficiency (n) are used to evaluate the performance of engine. The results show that, the engine power (Ne) is 10%-15% lower, the SFC of engine D243 using pure vegetable oils is 3%-5% higher and the η is 2.5%-6.2% lower compared to diesel oil (DO). Among the pure vegetable oils, the best performance results for D243 diesel engine are obtained from heated pure sunflower oil up to 135oC.

Introduction (problem statement and relevance). The object of research in this work is an inline six-cylinder gas engine 6ChN13/15 with a Miller thermodynamic cycle. On the basis of its computer model studies minimization of the specific effective fuel consumption has been reached due to variation study of gas distribution and air supply systems parameters.The purpose of the study was to investigate the parameters regulation effect of gas distribution and air supply systems on the performance of a 6ChN13/15 gas engine with a Miller cycle on the external speed characteristic basing on numerical modeling.Methodology and research methods. The research was carried out by the method of computer simulation. Numerical modeling was made on the basis of data obtained during a full-scale experiment of a 6ChN13/15 gas engine with Miller thermodynamic cycle.Scientific novelty and results. A comparative analysis of a gas engine optimization results has been carried out. The results obtained will be used to create a gas engine and its further optimization by controlling the working process and the air supply system.Practical significance. The results obtained may be of interest to truck car manufacturers and engine specialists.

Warm mix asphalt (WMA) is a recent technology used to reduce working temperatures without affecting the property of pavement. warm mix asphalt technology is a find out the optimum temperature of asphalt mixture. A number of WMA processes have been developed in recent days. One of the processes is the use of synthetic zeolite as an additive. A number or try in the laboratory to develop warm mix asphalt and using synthetic zeolite as an additive at a specified mixing and optimum temperature which were obtained after a number of trials. Warm mixing with additive is becoming popular because of mixing at a lower temperature which reduces the fuel usage and emission of hazardous gases consequently decreases the mixing as well as compaction temperature of the mix. Reduction of 20º C to 40º C has documented, such reduction has the obvious benefits of cutting fuel consumption and decreasing the production of greenhouse gases. Also, there will improvement in the performance of the pavement. In the present study, The mix asphalt with aggregate gradation as per MORTH specifications was made with varying binder contents (5%,6% and7%). The zeolite content was 0.3% by weight of aggregate. Stone dust and VG 30-grade Asphalt were used as a binder for the mixes. and the help of laboratory tests to find the physical properties of WMA with synthetic zeolite at optimum temperature. These additives are zeolites, that is, minerals of the aluminosilicate group, the crystalline structure of which contains water bound in a specific way. Its release, at mixed asphalt production temperatures, causes asphalt foaming. It is currently known that zeolites can be used in WMA, including natural and synthetic zeolites obtained using chemical reagents and waste. This review presents the results of studies of WMA technology, including the effects of zeolite addition on asphalt properties and mixes asphalt, as well as related environmental, economic, and technological benefits.

Introduction (problem statement and relevance). This article provides up-to-date information analysis of the crankcase gases bypass effect from the crankcase ventilation system to the compression ignition engine intake. The paper considers the information on the variants of the crankcase ventilation systems of modern engines. The article reveals the necessity to analyze the engine working process at the design and development stage of a closed crankcase ventilation system. The legislative requirements for the implementation of the ventilation system to ensure safe environmental performance have been indicated. The purpose of the study was to assess both open and closed ventilation system effect on the crankcase space indicators, in particular, on the average specific fuel consumption, with reference to a high-performance automobile engine with compression ignition.Methodology and research methods. Theoretical and computational studies were carried out with the help of mathematical statistics and thermodynamics methods in a one-dimensional setting. The verification of the calculations reliability was carried out by comparing the simulation data and the results the internal combustion engine experimental studies.Scientific novelty and results. A thermodynamic model of a high-performance automobile engine compression ignition V8 CHN 12/13 with an open and closed ventilation system of the crankcase space has been developed. The model made it possible to evaluate the effect of crankcase gases bypass back to the engine cylinder intake.Practical significance. The developed thermodynamic models confirmed the insignificant effect on the working process of the V8 CHN 12/13 engine by bypassing crankcase gases back to the cylinder inlet.

In this study, effect of anisole additive into the diesel fuel on performance and emission parameters of diesel engines was investigated. Instead of structural changes which are more difficult and expensive, development of fuel technologies is preferred to provide reduction on exhaust gas emissions which are harmful to environment and human health. Therefore, in this experimental study, anisole was used as additive into diesel fuel with the volumetric ratio of 1,5%, 3% and 5%. The performance characteristics and exhaust emissions of a four cylinder, four stroke, naturally aspirated, water cooled, direct injection compression ignition engine fueled with modified fuels were analyzed. Engine was subjected constant speed, full load conditions during tests. Engine power, torque, specific fuel consumption, carbon monoxide, nitrogen oxide and carbon dioxide emissions were measured and results were evaluated. Changes in performance parameters were negligible for all ratios of modified fuels except specific fuel consumption. Finally, while carbon monoxide gas emissions were increased with anisole additive, carbon dioxide and nitrogen oxide gas emissions were decreased.

The increase in greenhouse gas emissions and our dependence on fossil fuels have motivated researchers to seek the use of renewable fuels in internal combustion engines, which can be produced locally and have clean combustion. The blending method in diesel engines has been recognized as an effective alternative to partially or totally replace the use of diesel fuel. In this regard, this paper studied the operation of a small engine-generator set in mono-fuel mode (diesel fuel - DO) and in dual-fuel mode using hydrous ethanol (HET) and castor oil (OM) blends, indicating a total replacement of diesel fuel. Efficiency, power, specific fuel consumption and gaseous emissions were assessed in a single cylinder diesel cycle engine. The percentages in volume of the HET-OM samples were: 75% - 25%, 70% - 30%, 60% - 40%, and 50% - 50%. The exhaust gas temperature decreased with the mixtures. Carbon monoxide emission decreased 57%, carbon dioxide decreased 9.8%, and nitrogen oxides reduced 19%. It was also observed that the percentage of smoke opacity tends to decrease close to zero with addition of ethanol. Hydrocarbon emissions increased with rising of the OM concentration and the same for the specific fuel consumptions, which was 25.4% higher than diesel fuel. The best fuel conversion efficiency was achieved with the blend HET75-OM25, being 9% higher compared to diesel fuel operation. Power on diesel fuel operation showed a better result keeping stable, with the increase of the compression ratio and the delay of the start of injection. In general, the results confirmed that the performance is comparable to that of diesel fuel, indicating that renewable fuels appear as an alternative for the reduction of the environmental impacts and the reduction of fossil fuels consumption.

This paper describes the effect of a mixture of rapeseed methyl ester and diesel oil on fuel consumption and power parameters of tractor engine. The hydraulic dynamometer was used to load the engine of Zetor Forterra 8641 tractor over rear power take-off. The measured tractor is almost new with less than 100 h worked. The measurements were realized for several ratios of diesel oil and rapeseed methyl ester (from pure diesel to pure rapeseed methyl ester). The engine was loaded by the dynamometer in several working points which were predefined by engine speed and its torque. The fuel consumption was measured by the flow meter in each of these points. The reduction of engine’s power parameters and the increase of specific fuel consumption are expected due to the nature of rapeseed methyl ester such as e.g. lower calorific value.  

Biodiesel as a renewable and environmentally friendly alternative fuel derived from natural fats or vegetable oils has better lubricating properties and much higher cetane ratings than today's lower sulfur diesel fuels. It is considered as an attractive alternative to replace diesel fuels. In order to investigate application of biodiesel on vehicle diesel engines, the power and fuel economies performances of a diesel fueled soybean biodiesel with different blending ratios were tested under different engine loads and speeds. Experimental results show that, compared with diesel fuel, with increase in the biodiesel in the blends, the brake power and torque, and the brake specific energy consumption increase but the fuel consumption per hour and brake specific fuel consumption decrease.

Energy consumption and Greenhouse Gas (GHG) of major Alternative vehicle fuels (AVFs) in Thailand are estimated and compared with conventional fuels by means of full Life Cycle Assessment (LCA). The tool utilized here is the Well-to-Wheels (WtW) module of own model covering the entire lifecycle including: raw materials cultivation (or feedstock collection); fuel production; transportation and distribution; and application in automobile engines (ICE and hybrid engine), compared with conventional petroleum-based gasoline and diesel pathways. The model is based on Thailand’s national conditions with Tsinghua-CA3EM model. Part of this model structure has been adjusted to Thailand specific situations. Therefore, a majority of the parameters have been modified with local Thailand data. Results showed that the all alternative vehicle fuels can reduce energy consumption and GHG emissions compared to conventional fuels. Hybrid ICE engine to reduce energy consumption and GHG emissions when compared to the ICE engine. Biofuels-ICE engine, especially bioethanol from molasses, had the highest reduce energy consumption and GHG emissions. LPG- Hybrid ICE engine had the highest reduce energy consumption.

In this paper, biodiesel was used as an alternative fuel to investigate the combustion and emission characteristics of a four-stroke diesel engine, in terms of cylinder pressure, heat release rate, cylinder temperature, brake thermal efficiency, brake specific fuel consumption, nitrogen oxide, soot, carbon monoxide, and hydrocarbon. Firstly, a diesel engine cylinder model was developed by AVL-Fire software coupled with CHEMKIN code to simulate the injection and combustion of biodiesel with a kinetic mechanism with 106 species and 263 reactions. Then, the simulation model was validated by experimental results under 100% and 50% load conditions and used to simulate the combustion process of a diesel engine fueled with pure diesel, biodiesel, and biodiesel–diesel blends with 10%, 20%, 30% biodiesel by volume, respectively. The results showed that the brake specific fuel consumption increased with the increase of mixed biodiesel ratio. The brake specific fuel consumptions of B10, B20 and B30 increased by 1.1%, 2.3% and 3.3%, respectively, compared with that of D100. The combustion and emission characteristics of the diesel engine are improved. Therefore, biodiesel can be used as an alternative fuel for the diesel engine. The diesel–biodiesel fuel can improve the combustion and emission characteristics of the diesel engine.

Purpose of this project is a) the evaluation of the Thrust Specific Fuel Consumption (TSFC) of jet engines in cruise as a function of flight altitude, speed and thrust and b) the determination of the optimum cruise speed for maximum range of jet airplanes based on TSFC characteristics from a). Related to a) a literature review shows different models for the influence of altitude and speed on TSFC. A simple model describing the influence of thrust on TSFC seems not to exist in the literature. Here, openly available data was collected and evaluated. TSFC versus thrust is described by the so-called bucket curve with lowest TSFC at the bucket point at a certain thrust setting. A new simple equation was devised approximating the influence of thrust on TSFC. It was found that the influence of thrust as well as of altitude on TSFC is small and can be neglected in cruise conditions in many cases. However, TSFC is roughly a linear function of speed. This follows already from first principles. Related to b) it was found that the academically taught optimum flight speed (1.316 times minimum drag speed) for maximum range of jet airplanes is inaccurate, because the derivation is based on the unrealistic assumption of TSFC being constant with speed. Taking account of the influence of speed on TSFC and on drag, the optimum flight speed is only about 1.05 to 1.11 the minimum drag speed depending on aircraft weight. The amount of actual engine data was extremely limited in this project and the results will, therefore, only be as accurate as the input data. Results may only have a limited universal validity, because only four jet engine types were analyzed. One of the project's original value is the new simple polynomial function to estimate variations in TSFC from variations in thrust while maintaining constant speed and altitude.

The possibilities to simulate fuel consumption and optimize a vehicle's powertrain to fit to the customer's needs are great strengths in the competitive bus industry where fuel consumption is one of the main sales arguments. In this master's thesis, bus specific powertrain component models, used to simulate and predict fuel consumption, are validated using measured data collected from buses.

Additionally, a sensitivity analysis is made where it is investigated how errors in the powertrain parameters affect fuel consumption. After model improvements it is concluded that the library components can be used to predict fuel consumption well.

During the work, possible model uncertainties which affect fuel consumption are identified. Hence, this study may serve as foundation for further investigation of these uncertainties.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O trator agrícola é a principal fonte de potência utilizada na agricultura e a maioria dos novos modelos disponíveis no mercado apresenta tração dianteira auxiliar (TDA). A preferência pelos tratores com tração dianteira auxiliar é devido à sua maior capacidade de tração, principalmente em condições trativas adversas e, sobretudo pela relação benefício e custo ser positiva e maior que os outros modelos. Esse trabalho foi realizado com o objetivo de avaliar o rendimento dinâmico na barra de tração de tratores agrícolas com tração dianteira auxiliar (4x2 TDA) em diferentes condições de superfície trativa comparando-os com os valores teóricos e práticos da bibliografia (“Fator 0,86” de Wendel Bowers e norma D497.4 ASAE, 1999) e determinar o rendimento dinâmico na barra para a superfície de solo com cobertura vegetal, pois existe pouca bibliografia e é uma realidade no Brasil com o plantio direto na palha. Avaliaram-se onze tratores agrícolas em diversas condições de ensaio de campo e condições de superfície, variando-se o tipo construtivo e modelos de conjunto de pneus, pressões de inflação dos pneus, relações entre o peso e potência do motor e velocidade teórica de deslocamento. Os dados de rendimento máximo na barra de tração do trator obtidos nos ensaios foram arranjados em grupos, obtendo-se o rendimento dinâmico médio na barra de tração e desvio padrão para cada condição de superfície. Foram coletados os dados para o cálculo do rendimento na barra de tração do trator, velocidade de deslocamento, patinagem das rodas dianteiras e traseiras do trator, consumo de combustível, força de tração e potência disponível na barra de tração.a realização do experimento, utilizou-se a Unidade Móvel de Ensaio...
The agricultural tractor is the main power source used in the agriculture and the most of available new tractor models in the marketing present auxiliary front drive (4WD). The preference for the 4WD tractors is due to biggest traction capacity, mainly in adverse tractive conditions and, mainly for the relationship benefit and cost to be positive and larger than the other models. This research was accomplished with the objective to evaluate the dynamic drawbar performance of several agricultural tractors 4WD in different surface condition (concrete, firm soil and tilled soil) comparing them with the theoretical and practical values of the bibliography (Wendel Bowers 0.86 Factor and D497.4 ASAE standard, 1999) and to determine the dynamic drawbar performance for the soil surface with vegetable covering, that doesn't exist in the bibliography and it is a reality in Brazil with the minimum cultivate. Eleven agricultural tractors were evaluated all 4WD in several field test conditions and surface conditions, being varied the tire constructive type and models, tire inflation pressures, relationships between the weight and engine power and forward speed. The maximum tractor drawbar performance obtained in the tests was arranged in groups, being obtained the medium dynamic drawbar... (Complete abstract click electronic access below)

Thesis: Nav. E., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.
Thesis: S.M. in Naval Architecture and Marine Engineering, Massachusetts Institute of Technology, Department of Mechanical Engineering, 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages [71a]-[71b]).
The dynamic operational nature of naval power and propulsion requires Ship Design and Program Managers to design and select prime movers using a much more complex speed profile rather than typical of commercial vessels. The inherently reduces the overall efficiency of the plant as operated in comparison to its potential. The fuel consumption of prime movers is a multi-variable function of power demand and rotational speed. Mechanically coupled power and propulsion arrangements constrain this two degree of freedom relationship by removing the independence of the speed parameter. Fixed frequency power generation requires a constant prime mover speed that has a narrow power band for optimal fuel consumption. Likewise, geared propulsion arrangements restrict the prime mover's speed to a dependence on the combined propulsor thrust-hull resistance performance which generally follows a cubic function. Optimal fuel consumption, however, involves matching the load's efficiency performance to that of the prime mover. This requires the rotational speed of the prime mover to be an independent variable with the freedom to adjust to the lowest specific fuel consumption for the demanded power. Variable frequency drive (VFD) concepts offer relief of this constraint but at a cost in the form of increased power conversion and control support system footprints. The ever increasing and complex demands for electrical power increases the motivation and interest in innovative technologies that improving current design concepts. Incorporating doubly fed electric machines (DFEM) into the power and propulsion design architecture enables the efficiency results of a VFD system but with a smaller conversion and control support footprint. The Navy has invested resources into research and development of several electric power and propulsion technologies enabling deployment of VFD systems on a handful of ship classes. The wind power generation industry has matured many aspects of DFEM technology. Leveraging this experience into naval engineering applications could help facilitate additional platform types and sizes to benefit from the operational advantages of integrated electrical architectures. Applying DFEM concepts to naval engineering requires a horizontal transfer of the body of knowledge. Researchers in the field of DFEM technology need to gain a better understanding of the intricacies of integrating a marine vessel's engineering plant with the vessel's designed purpose. New methods of analysis tailored specifically to marine power and propulsion require development for the technology to be properly assessed. This study outlines the various issues challenging ship designers and explains the manner in which DFEM research can be continued in naval engineering. Finally a method of examining a prime mover's fuel consumption is developed to provide a three-dimensional "fuel map" surface relationship of power-to-speed-to-fuel consumption. This thesis will serve as a building block supporting further DFEM power and propulsion concept analysis.
by Michael R. Rowles, Jr.
Nav. E.
S.M. in Naval Architecture and Marine Engineering

Orientador: Kléber Pereira Lanças
Banca: Alberto Kazushi Nagaoka
Banca: Paulo Roberto Arbex Silva
Resumo: O trator agrícola é a principal fonte de potência utilizada na agricultura e a maioria dos novos modelos disponíveis no mercado apresenta tração dianteira auxiliar (TDA). A preferência pelos tratores com tração dianteira auxiliar é devido à sua maior capacidade de tração, principalmente em condições trativas adversas e, sobretudo pela relação benefício e custo ser positiva e maior que os outros modelos. Esse trabalho foi realizado com o objetivo de avaliar o rendimento dinâmico na barra de tração de tratores agrícolas com tração dianteira auxiliar (4x2 TDA) em diferentes condições de superfície trativa comparando-os com os valores teóricos e práticos da bibliografia ("Fator 0,86" de Wendel Bowers e norma D497.4 ASAE, 1999) e determinar o rendimento dinâmico na barra para a superfície de solo com cobertura vegetal, pois existe pouca bibliografia e é uma realidade no Brasil com o plantio direto na palha. Avaliaram-se onze tratores agrícolas em diversas condições de ensaio de campo e condições de superfície, variando-se o tipo construtivo e modelos de conjunto de pneus, pressões de inflação dos pneus, relações entre o peso e potência do motor e velocidade teórica de deslocamento. Os dados de rendimento máximo na barra de tração do trator obtidos nos ensaios foram arranjados em grupos, obtendo-se o rendimento dinâmico médio na barra de tração e desvio padrão para cada condição de superfície. Foram coletados os dados para o cálculo do rendimento na barra de tração do trator, velocidade de deslocamento, patinagem das rodas dianteiras e traseiras do trator, consumo de combustível, força de tração e potência disponível na barra de tração.a realização do experimento, utilizou-se a Unidade Móvel de Ensaio... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The agricultural tractor is the main power source used in the agriculture and the most of available new tractor models in the marketing present auxiliary front drive (4WD). The preference for the 4WD tractors is due to biggest traction capacity, mainly in adverse tractive conditions and, mainly for the relationship benefit and cost to be positive and larger than the other models. This research was accomplished with the objective to evaluate the dynamic drawbar performance of several agricultural tractors 4WD in different surface condition (concrete, firm soil and tilled soil) comparing them with the theoretical and practical values of the bibliography (Wendel Bowers "0.86 Factor" and D497.4 ASAE standard, 1999) and to determine the dynamic drawbar performance for the soil surface with vegetable covering, that doesn't exist in the bibliography and it is a reality in Brazil with the minimum cultivate. Eleven agricultural tractors were evaluated all 4WD in several field test conditions and surface conditions, being varied the tire constructive type and models, tire inflation pressures, relationships between the weight and engine power and forward speed. The maximum tractor drawbar performance obtained in the tests was arranged in groups, being obtained the medium dynamic drawbar... (Complete abstract click electronic access below)
Mestre

Zapfluft und Wellenleistung wird den Triebwerken entnommen, um die Energie für beispielsweise die Kraftstoffpumpen, das Inflight Entertainment oder die Flügelvorderkantenenteisung zu erzeugen. Diese Energiegenerierung, hat einen Anstieg des Kraftstoffverbrauches zur Folge. Es hat sich herausgestellt, dass die Stelle der Zapfluftentnahme einen starken Einfluss auf den Gradienten des Brennstoffverbrauches hat. Das Projekt beschäftigt sich mit zwei- und dreiwelligen Turbofantriebwerken und untersucht an ihnen, die Effekte der Leistungsnahmen. Als Simulationssoftware wurde GasTurb 8.0 eingesetzt und auf die integrierten Triebwerkskonfigurationen zurückgegriffen. Ziel der Arbeit ist die Ermittlung einer mathematischen Beziehung zur Berechnung des zusätzlichen Kraftstoffmassenstromes infolge einer Zapfluft- oder Wellenleistungsentnahme. So stellt sich die Frage, welche Triebwerksparameter dafür berücksichtigt werden müssen. Eine Wellenleistungsentnahme verursacht beispielsweise einen linearen Anstieg des spezifischen Kraftstoffverbrauches. Ist diese Zunahme, identisch mit der einer Zapfluftentnahme? Am Ende der Kapitel werden die Ergebnisse mit Literaturwerten verglichen und versucht Tendenzen zu erkennen bzw. bestehende zu erhärten.

In the development of modern rotorcraft vehicles, many unique challenges emerge due to the highly coupled nature of individual rotorcraft design disciplines therefore, the use of an integrated product and process development (IPPD) methodology is necessary to drive the design solution. Through the use of parallel design and analysis, this approach achieves the design synthesis of numerous product and process requirements that is essential in ultimately satisfying the customers demands. Over the past twenty years, Georgia Techs Center for Excellence in Rotorcraft Technology (CERT) has continuously focused on refining this IPPD approach within its rotorcraft design course by using the annual American Helicopter Society (AHS) Student Design Competition as the design requirement catalyst. Despite this extensive experience, however, the documentation of this preliminary rotorcraft design approach has become out of date or insufficient in addressing a modern IPPD methodology. In no design discipline is this need for updated documentation more prevalent than in propulsion system design, specifically in the area of gas turbine technology. From an academic perspective, the vast majority of current propulsion system design resources are focused on fixed-wing applications with very limited reference to the use of turboshaft engines. Additionally, most rotorcraft design resources are centered on aerodynamic considerations and largely overlook propulsion system integration. This research effort is aimed at bridging this information gap by developing a preliminary turboshaft engine design methodology that is applicable to a wide range of potential rotorcraft propulsion system design problems. The preliminary engine design process begins by defining the design space through analysis of the initial performance and mission requirements dictated in a given request for proposal (RFP). Engine cycle selection is then completed using tools such as GasTurb and the NASA Engine Performance Program (NEPP) to conduct thorough parametric and engine performance analysis. Basic engine component design considerations are highlighted to facilitate configuration trade studies and to generate more detailed engine performance and geometric data. Throughout this approach, a comprehensive engine design case study is incorporated based on a two-place, turbine training helicopter known as the Georgia Tech Generic Helicopter (GTGH). This example serves as a consistent propulsion system design reference highlighting the level of integration and detail required for each step of the preliminary turboshaft engine design methodology.

This thesis deals with the use of the tractor in agricultural transport. The first part describes the current status in construction of tractor engines, transmissions and chassis that are used in tractors suitable for transport. The theoretical section includes an overview of the legislative requirements that must be followed for the tractor kits in transport on the road. The main objective of this thesis was to evaluate a measuring of fuel consumption and efficiency of the tractor JCB Fastrac 185-65 with two flatbed trailers. For this purpose was created the methodics off terrain measurement, which were carried out for different operation modes of the engine. The results were tabular and graphical processing including determining the accuracy of the method by calculating the relative error of measurement. For comparison a theoretical calculation of the consumed fuel was made. The aim of the measurements was to demonstrate fuel-saving during operation engine in the economic field and get an overview about fuel consumption and efficiency kits.

The thesis deals with the current situation in the construction of tractors, particularly engines and accessories. The work includes a methodology for measuring tractor rigs in traffic as well as methodology for plough/plow kits measuring. The measured values were tabulated, graphically presented and analysed. The thesis provides an overview of the issue of the combustion engine load placed on the engine by working conditions in transport, during primary soil tillage with different modes of operation of the tractor set. The thesis aim is to find out the practical effect of the engine load on the monitored parameters and to indicate possibilities for achieving higher efficiency in tractor units with minimum fuel performance

AbstractThis chapter describes four pilot cases covering the Norwegian pelagic fisheries for small fish species in the North Atlantic Ocean, such as mackerel, herring and blue whiting. The pilot cases aim to improve sustainability and value creation. Big data methods and tools have been used to demonstrate the potential impact on fuel consumption, fisheries planning and fish stock assessments. Specifically, the pilots have targeted immediate operational choices, short-term fisheries planning, fish stock assessments and longer-term market predictions.

AbstractThe paper uses the case study of Limpopo province to discuss technology innovations in green transport in South Africa with respect to the reduction of global greenhouse emission through technology innovation. South Africa’s emission from fuel combustion is the world’s 15th largest in forms of CO emission because it contributes about 1.2% of global emissions. In a submission from the Department of Environmental Affairs (DEA) on the impact of greenhouse emissions stated that companies are required to be innovative to reduce the carbon emission levels in South Africa. Literature on road transport in South Africa shows that road transport is the fastest growing source of greenhouse gas emissions, accounting for 19% of global energy consumption. The policy to promote an integrated public transport in municipalities is in line with the National Development Plan and the White Paper on National Climate Change Response. This requires innovative technology that promotes carbon trading markets such as taxi recapitalisation programmes and carbon tax on new vehicles. The study analysed the factors influencing green technology innovations in South Africa with specific reference to Limpopo province green transportation study. The methodology used to unpack innovative technology in South Africa discusses green technology in Limpopo province in the context of greenhouse gases emission reduction innovative technologies in the transport sector with respect to sustainable fuels, energy efficient systems and smart information as well as hybrid technologies. The study advances arguments on technologies for engine and propulsion systems, alternative energy sources, navigation technologies, cargo handling systems, heating and cooling vehicles, road and rail vehicles and maritime transportation with respect to innovations as well as battery charging systems, engine oil disposal etc. The findings shows that no single trajectory of technology innovation in green transport will suffice but technological innovations that improve fuel economy and transition from fossil fuels to cleaner fuel alternatives. The study in Limpopo province showed that green transport innovations must not obscure the role of non-technological innovations in reducing emissions, but the two should be tackled with green transport value chain as a whole.

AbstractThe increasing demand for performance improvements in radiation detectors, driven by cutting-edge research in nuclear physics, astrophysics and medical imaging, is causing not only a proliferation in the variety of the radiation sensors, but also a growing necessity of tailored solutions for the front-end readout electronics. Within this work, novel solutions for application specific integrated circuits (ASICs) adopted in high-resolution X and $$\upgamma $$ γ ray spectroscopy applications are studied. In the first part of this work, an ultra-low noise charge sensitive amplifier (CSA) is presented, with specific focus on sub-microsecond filtering, addressing the growing interest in high-luminosity experiments. The CSA demonstrated excellent results with Silicon Drift Detectors (SDDs), and with room temperature Cadmium-Telluride (CdTe) detectors, recording a state-of-the-art noise performance. The integration of the CSA within two full-custom radiation detection instruments realized for the ELETTRA (Trieste, Italy) and SESAME (Allan, Jordan) synchrotrons is also presented. In the second part of this work, an ASIC constellation designed for X-Gamma imaging spectrometer (XGIS) onboard of the THESEUS space mission is described. The presented readout ASIC has a highly customized distributed architecture, and integrates a complete on-chip signal filtering, acquisition and digitization with an ultra-low power consumption.

AbstractEuropean final energy consumption mainly stems from five sectors: transport, households, industry, residential, and agriculture using fossil fuels as dominant energy carriers. In order to achieve the climate targets, emissions in the demand sectors must be drastically reduced. Due to different characteristics and challenges each sector needs its own strategy how to achieve such decarbonization until 2050. In the following chapter, the impacts of an ambitious mitigation scenario on future energy demand and CO2 emissions for transport, industry, residential, and tertiary are analyzed discussing sector specific decarbonization strategies and mitigation options. Implications of such strategies for demand-side flexibility and its future need are analyzed.

AbstractCities, and general urban areas, contribute critically to climate change because of the GHGs related to traffic congestion, fossil fuel consumption, noise and air pollution. Air pollution, despite the noteworthy improvements during the last decades, still plays a significant role in the quality of living in European cities as it causes damages to health and ecosystems, thus making urgent the immoderate need of diminishing it. Within the Horizon 2020 CIVITAS DESTINATIONS project, six European island cities, which are highly attractive destinations for tourists worldwide, implemented various sustainable mobility measures. Among them, Funchal, Madeira-Portugal, and Rethymno, Crete-Greece, implemented two different environmental monitoring systems to measure and calculate a predetermined set of indicators, capable of estimating the environmental benefits in transport, economy, society, energy, and the environment. The monitoring systems were installed in specific sites all around these two cities, aiming, through the integrated sensors, to collect environmental data related to transport load, such as environmental indexes (temperature, humidity, noise) and air pollutants (CO2, CO, NOx, SO2, PM). The collection of critical and reliable data offers the opportunity for an effective evaluation of the overall performance of the implemented measures toward sustainable, environmentally friendly, and low-carbon mobility policies.

AbstractIn this final chapter, we summarize the DataBio learnings about how to exploit big data and AI in bioeconomy. The development platform for the software used in the 27 pilots was a central tool. The Enterprise Architecture model Archimate laid a solid basis for the complex software in the pilots. Handling data from sensors and earth observation were shown in numerous pilots. Genomic data from crop species allows us to significantly speed up plant breeding by predicting plant properties in-silico. Data integration is crucial and we show how linked data enables searches over multiple datasets. Real-time processing of events provides insights for fast decision-making, for example about ship engine conditions. We show how sensitive bioeconomy data can be analysed in a privacy-preserving way. The agriculture pilots show with clear numbers the impact of big data and AI on precision agriculture, insurance and subsidies control. In forestry, DataBio developed several big data tools for forest monitoring. In fishery, we demonstrate how to reduce maintenance cost and time as well as fuel consumption in the operation of fishing vessels as well as how to accurately predict fish catches. The chapter ends with perspectives on earth observation, machine learning, data sharing and crowdsourcing.

The aim of this study is to develop the one-dimensional model of a four-cylinder, four-stroke, multi-point injection system SI engine and a direct injection system SI engine for predicting the effect of various fuel types on engine performances, specific fuel consumption, and emissions. Commercial software AVL BOOST was used to examine the engine characteristics for different blends of methanol and gasoline (by volume: 5% methanol [M5], 10% methanol [M10], 20% methanol [M20], 30% methanol [M30], and 50% methanol [M50]). The methanol-gasoline fuel blend results were compared to those of net gasoline fuel. The obtained results show that when methanol-gasoline fuel blends were used, engine performance such as power and torque increases and the brake-specific fuel consumption increases with increasing methanol percentage in the blended fuel.

Cruise specific fuel consumption (SFC) of turbofan engines is a key metric for increasing airline profitability and for reducing CO2 emissions. Although increasing design bypass ratio (BPR) of separate exhaust turbofan configurations improves cruise SFC, further improvements can be obtained with control actuated variable geometry modulations of core nozzle throat area, bypass nozzle throat area, and compressor variable vanes (CVV). The scope of this paper is to show only the benefits possible, and the process used in determining those benefits, and not to suggest any particular control algorithm for searching the best combination of the control effectors. A parametric cycle study indicated that the effector modulations could increase the cruise BPR, core efficiency, transmission efficiency, propulsive efficiency, and ideal velocity ratio resulting in a cruise SFC improvement of as much as 2.6% depending upon the engine configuration. The changes in these metrics with control effector variations will be presented. Modulation of CVV is already possible in legacy digital controls, and modulation of nozzle areas should be explored in light of the low bandwidth requirements at steady-state cruise conditions.

Abstract Fuel consumption reduction and emission reductions in internal combustion engines (ICE) is a hot topic nowadays. An adaption of cylinder de-activation technique called ECONAMIQ over-expansion can be applied to engines to improve fuel efficiency. Using the pressure from the exhaust gas from the active cylinders, the ‘idle’ cylinders could be expanded to extract more work out of the engine during partial load operation. Using the virtual simulation environment GT-Power, this cycle is applied to a 4-cylinder SI engine. This engine model is simulated for a part load operation point and compared with a standard 4-cylinder engine model and 4-cylinder engine model equipped with cylinder de-activation. From these simulations various variables for engine operation (valve timing etc.) are optimized to further reduce fuel consumption of the engine. A final brake specific fuel consumption reduction of over 10% is achieved using the overexpansion cycle, while improving engine performance on two burning cylinders over 10% as well. With this improvement it is shown that the over-expansion cycle has a significant benefit compared to a standard ICE and cylinder de-activation techniques. These simulations are being validated on an engine test dyno using a natural aspirated ICE.

The major bottlenecks in rearing the highly priced gastropod abalone (Haliotis spp.) are the slow growth rate and the high mortality during the first 8 to 12 weeks following metamorphosis and settling. The most likely reason flor these problems is related to nutritional deficiencies in the diatom diet on which the post larvae (PL) feed almost exclusively in captivity. Higher survival and improved growth rate will reduce the considerable expense of hatchery-nursery resisdence time and thereflore the production costs. BARD supported our research for one year only and the support was given to us in order to prove that "(1) Abalone PL feed on encapsulated diatoms, and (2) heterotrophic diatoms can be mass produced." In the course of this year we have developed a novel nutrient delivery system specifically designed to enhance growth and survival of post-larval abalone. This approach is based on the sodium-alginate encapsulation of heterotrophically grown diatoms or diatom extracts, including appetite-stimulating factors. Diatom species that attract the PL and promote the highest growth and survival have been identified. These were also tested by incorporating them (either intact cells or as cell extracts) into a sodium-alginate matrix while comparing the growth to that achieved when using diatoms (singel sp. or as a mixture). A number of potential chemoattractants to act as appetite-stimulating factors for abalone PL have been tested. Preliminary results show that the incorporation of the amino acid methionine at a level of 10-3M to the sodim alginate matrix leads to a marked enhancement of growth. The results ol these studies provided basic knowledge on the growth of abalone and showed that it is possible to obtain, on a regular basis, survival rates exceeding 10% for this stage. Prior to this study the survival rates ranged between 2-4%, less than half of the values achieved today. Several diatom species originated from the National Center for Mariculture (Nitzchia laevis, Navicula lenzi, Amphora T3, and Navicula tennerima) and Cylindrotheca fusiformis (2083, 2084, 2085, 2086 and 2087 UTEX strains, Austin TX) were tested for heterotrophic growth. Axenic colonies were initially obtained and following intensive selection cycles and mutagenesis treatments, Amphora T3, Navicula tennerima and Cylindrotheca fusiformis (2083 UTEX strain) were capable of growing under heterotrophic conditions and to sustain highly enriched mediums. A highly efficient selection procedure as well as cost effective matrix of media components were developed and optimized. Glucose was identified as the best carbon source for all diatom strains. Doubling times ranging from 20-40 h were observed, and stable heterotroph cultures at a densities range of 103-104 were achieved. Although current growth rates are not yet sufficient for full economical fermentation, we estimate that further selections and mutagenesis treatments cycles should result in much faster growing colonies suitable for a fermentor scale-up. As rightfully pointed out by one of the reviewers, "There would be no point in assessing the optimum levels of dietary inclusions into micro-capsules, if the post-larvae cannot be induced to consume those capsules in the first place." We believe that the results of the first year of research provide a foundationfor the continuation of this research following the objectives put forth in the original proposal. Future work should concentrate on the optimization of incorporation of intact cells and cell extracts of the developed heterotrophic strains in the alginate matrix, as well as improving this delivery system by including liposomes and chemoattractants to ensure food consumption and enhanced growth.

The objectives of this project were to develop nondestructive methods for detection of internal properties and firmness of fruits and vegetables. One method was based on a soft piezoelectric film transducer developed in the Technion, for analysis of fruit response to low-energy excitation. The second method was a dot-matrix piezoelectric transducer of North Carolina State University, developed for contact-pressure analysis of fruit during impact. Two research teams, one in Israel and the other in North Carolina, coordinated their research effort according to the specific objectives of the project, to develop and apply the two complementary methods for quality control of agricultural commodities. In Israel: An improved firmness testing system was developed and tested with tropical fruits. The new system included an instrumented fruit-bed of three flexible piezoelectric sensors and miniature electromagnetic hammers, which served as fruit support and low-energy excitation device, respectively. Resonant frequencies were detected for determination of firmness index. Two new acoustic parameters were developed for evaluation of fruit firmness and maturity: a dumping-ratio and a centeroid of the frequency response. Experiments were performed with avocado and mango fruits. The internal damping ratio, which may indicate fruit ripeness, increased monotonically with time, while resonant frequencies and firmness indices decreased with time. Fruit samples were tested daily by destructive penetration test. A fairy high correlation was found in tropical fruits between the penetration force and the new acoustic parameters; a lower correlation was found between this parameter and the conventional firmness index. Improved table-top firmness testing units, Firmalon, with data-logging system and on-line data analysis capacity have been built. The new device was used for the full-scale experiments in the next two years, ahead of the original program and BARD timetable. Close cooperation was initiated with local industry for development of both off-line and on-line sorting and quality control of more agricultural commodities. Firmalon units were produced and operated in major packaging houses in Israel, Belgium and Washington State, on mango and avocado, apples, pears, tomatoes, melons and some other fruits, to gain field experience with the new method. The accumulated experimental data from all these activities is still analyzed, to improve firmness sorting criteria and shelf-life predicting curves for the different fruits. The test program in commercial CA storage facilities in Washington State included seven apple varieties: Fuji, Braeburn, Gala, Granny Smith, Jonagold, Red Delicious, Golden Delicious, and D'Anjou pear variety. FI master-curves could be developed for the Braeburn, Gala, Granny Smith and Jonagold apples. These fruits showed a steady ripening process during the test period. Yet, more work should be conducted to reduce scattering of the data and to determine the confidence limits of the method. Nearly constant FI in Red Delicious and the fluctuations of FI in the Fuji apples should be re-examined. Three sets of experiment were performed with Flandria tomatoes. Despite the complex structure of the tomatoes, the acoustic method could be used for firmness evaluation and to follow the ripening evolution with time. Close agreement was achieved between the auction expert evaluation and that of the nondestructive acoustic test, where firmness index of 4.0 and more indicated grade-A tomatoes. More work is performed to refine the sorting algorithm and to develop a general ripening scale for automatic grading of tomatoes for the fresh fruit market. Galia melons were tested in Israel, in simulated export conditions. It was concluded that the Firmalon is capable of detecting the ripening of melons nondestructively, and sorted out the defective fruits from the export shipment. The cooperation with local industry resulted in development of automatic on-line prototype of the acoustic sensor, that may be incorporated with the export quality control system for melons. More interesting is the development of the remote firmness sensing method for sealed CA cool-rooms, where most of the full-year fruit yield in stored for off-season consumption. Hundreds of ripening monitor systems have been installed in major fruit storage facilities, and being evaluated now by the consumers. If successful, the new method may cause a major change in long-term fruit storage technology. More uses of the acoustic test method have been considered, for monitoring fruit maturity and harvest time, testing fruit samples or each individual fruit when entering the storage facilities, packaging house and auction, and in the supermarket. This approach may result in a full line of equipment for nondestructive quality control of fruits and vegetables, from the orchard or the greenhouse, through the entire sorting, grading and storage process, up to the consumer table. The developed technology offers a tool to determine the maturity of the fruits nondestructively by monitoring their acoustic response to mechanical impulse on the tree. A special device was built and preliminary tested in mango fruit. More development is needed to develop a portable, hand operated sensing method for this purpose. In North Carolina: Analysis method based on an Auto-Regressive (AR) model was developed for detecting the first resonance of fruit from their response to mechanical impulse. The algorithm included a routine that detects the first resonant frequency from as many sensors as possible. Experiments on Red Delicious apples were performed and their firmness was determined. The AR method allowed the detection of the first resonance. The method could be fast enough to be utilized in a real time sorting machine. Yet, further study is needed to look for improvement of the search algorithm of the methods. An impact contact-pressure measurement system and Neural Network (NN) identification method were developed to investigate the relationships between surface pressure distributions on selected fruits and their respective internal textural qualities. A piezoelectric dot-matrix pressure transducer was developed for the purpose of acquiring time-sampled pressure profiles during impact. The acquired data was transferred into a personal computer and accurate visualization of animated data were presented. Preliminary test with 10 apples has been performed. Measurement were made by the contact-pressure transducer in two different positions. Complementary measurements were made on the same apples by using the Firmalon and Magness Taylor (MT) testers. Three-layer neural network was designed. 2/3 of the contact-pressure data were used as training input data and corresponding MT data as training target data. The remaining data were used as NN checking data. Six samples randomly chosen from the ten measured samples and their corresponding Firmalon values were used as the NN training and target data, respectively. The remaining four samples' data were input to the NN. The NN results consistent with the Firmness Tester values. So, if more training data would be obtained, the output should be more accurate. In addition, the Firmness Tester values do not consistent with MT firmness tester values. The NN method developed in this study appears to be a useful tool to emulate the MT Firmness test results without destroying the apple samples. To get more accurate estimation of MT firmness a much larger training data set is required. When the larger sensitive area of the pressure sensor being developed in this project becomes available, the entire contact 'shape' will provide additional information and the neural network results would be more accurate. It has been shown that the impact information can be utilized in the determination of internal quality factors of fruit. Until now,

1.1 Macroeconomic summary Economic recovery has consistently outperformed the technical staff’s expectations following a steep decline in activity in the second quarter of 2020. At the same time, total and core inflation rates have fallen and remain at low levels, suggesting that a significant element of the reactivation of Colombia’s economy has been related to recovery in potential GDP. This would support the technical staff’s diagnosis of weak aggregate demand and ample excess capacity. The most recently available data on 2020 growth suggests a contraction in economic activity of 6.8%, lower than estimates from January’s Monetary Policy Report (-7.2%). High-frequency indicators suggest that economic performance was significantly more dynamic than expected in January, despite mobility restrictions and quarantine measures. This has also come amid declines in total and core inflation, the latter of which was below January projections if controlling for certain relative price changes. This suggests that the unexpected strength of recent growth contains elements of demand, and that excess capacity, while significant, could be lower than previously estimated. Nevertheless, uncertainty over the measurement of excess capacity continues to be unusually high and marked both by variations in the way different economic sectors and spending components have been affected by the pandemic, and by uneven price behavior. The size of excess capacity, and in particular the evolution of the pandemic in forthcoming quarters, constitute substantial risks to the macroeconomic forecast presented in this report. Despite the unexpected strength of the recovery, the technical staff continues to project ample excess capacity that is expected to remain on the forecast horizon, alongside core inflation that will likely remain below the target. Domestic demand remains below 2019 levels amid unusually significant uncertainty over the size of excess capacity in the economy. High national unemployment (14.6% for February 2021) reflects a loose labor market, while observed total and core inflation continue to be below 2%. Inflationary pressures from the exchange rate are expected to continue to be low, with relatively little pass-through on inflation. This would be compatible with a negative output gap. Excess productive capacity and the expectation of core inflation below the 3% target on the forecast horizon provide a basis for an expansive monetary policy posture. The technical staff’s assessment of certain shocks and their expected effects on the economy, as well as the presence of several sources of uncertainty and related assumptions about their potential macroeconomic impacts, remain a feature of this report. The coronavirus pandemic, in particular, continues to affect the public health environment, and the reopening of Colombia’s economy remains incomplete. The technical staff’s assessment is that the COVID-19 shock has affected both aggregate demand and supply, but that the impact on demand has been deeper and more persistent. Given this persistence, the central forecast accounts for a gradual tightening of the output gap in the absence of new waves of contagion, and as vaccination campaigns progress. The central forecast continues to include an expected increase of total and core inflation rates in the second quarter of 2021, alongside the lapse of the temporary price relief measures put in place in 2020. Additional COVID-19 outbreaks (of uncertain duration and intensity) represent a significant risk factor that could affect these projections. Additionally, the forecast continues to include an upward trend in sovereign risk premiums, reflected by higher levels of public debt that in the wake of the pandemic are likely to persist on the forecast horizon, even in the context of a fiscal adjustment. At the same time, the projection accounts for the shortterm effects on private domestic demand from a fiscal adjustment along the lines of the one currently being proposed by the national government. This would be compatible with a gradual recovery of private domestic demand in 2022. The size and characteristics of the fiscal adjustment that is ultimately implemented, as well as the corresponding market response, represent another source of forecast uncertainty. Newly available information offers evidence of the potential for significant changes to the macroeconomic scenario, though without altering the general diagnosis described above. The most recent data on inflation, growth, fiscal policy, and international financial conditions suggests a more dynamic economy than previously expected. However, a third wave of the pandemic has delayed the re-opening of Colombia’s economy and brought with it a deceleration in economic activity. Detailed descriptions of these considerations and subsequent changes to the macroeconomic forecast are presented below. The expected annual decline in GDP (-0.3%) in the first quarter of 2021 appears to have been less pronounced than projected in January (-4.8%). Partial closures in January to address a second wave of COVID-19 appear to have had a less significant negative impact on the economy than previously estimated. This is reflected in figures related to mobility, energy demand, industry and retail sales, foreign trade, commercial transactions from selected banks, and the national statistics agency’s (DANE) economic tracking indicator (ISE). Output is now expected to have declined annually in the first quarter by 0.3%. Private consumption likely continued to recover, registering levels somewhat above those from the previous year, while public consumption likely increased significantly. While a recovery in investment in both housing and in other buildings and structures is expected, overall investment levels in this case likely continued to be low, and gross fixed capital formation is expected to continue to show significant annual declines. Imports likely recovered to again outpace exports, though both are expected to register significant annual declines. Economic activity that outpaced projections, an increase in oil prices and other export products, and an expected increase in public spending this year account for the upward revision to the 2021 growth forecast (from 4.6% with a range between 2% and 6% in January, to 6.0% with a range between 3% and 7% in April). As a result, the output gap is expected to be smaller and to tighten more rapidly than projected in the previous report, though it is still expected to remain in negative territory on the forecast horizon. Wide forecast intervals reflect the fact that the future evolution of the COVID-19 pandemic remains a significant source of uncertainty on these projections. The delay in the recovery of economic activity as a result of the resurgence of COVID-19 in the first quarter appears to have been less significant than projected in the January report. The central forecast scenario expects this improved performance to continue in 2021 alongside increased consumer and business confidence. Low real interest rates and an active credit supply would also support this dynamic, and the overall conditions would be expected to spur a recovery in consumption and investment. Increased growth in public spending and public works based on the national government’s spending plan (Plan Financiero del Gobierno) are other factors to consider. Additionally, an expected recovery in global demand and higher projected prices for oil and coffee would further contribute to improved external revenues and would favor investment, in particular in the oil sector. Given the above, the technical staff’s 2021 growth forecast has been revised upward from 4.6% in January (range from 2% to 6%) to 6.0% in April (range from 3% to 7%). These projections account for the potential for the third wave of COVID-19 to have a larger and more persistent effect on the economy than the previous wave, while also supposing that there will not be any additional significant waves of the pandemic and that mobility restrictions will be relaxed as a result. Economic growth in 2022 is expected to be 3%, with a range between 1% and 5%. This figure would be lower than projected in the January report (3.6% with a range between 2% and 6%), due to a higher base of comparison given the upward revision to expected GDP in 2021. This forecast also takes into account the likely effects on private demand of a fiscal adjustment of the size currently being proposed by the national government, and which would come into effect in 2022. Excess in productive capacity is now expected to be lower than estimated in January but continues to be significant and affected by high levels of uncertainty, as reflected in the wide forecast intervals. The possibility of new waves of the virus (of uncertain intensity and duration) represents a significant downward risk to projected GDP growth, and is signaled by the lower limits of the ranges provided in this report. Inflation (1.51%) and inflation excluding food and regulated items (0.94%) declined in March compared to December, continuing below the 3% target. The decline in inflation in this period was below projections, explained in large part by unanticipated increases in the costs of certain foods (3.92%) and regulated items (1.52%). An increase in international food and shipping prices, increased foreign demand for beef, and specific upward pressures on perishable food supplies appear to explain a lower-than-expected deceleration in the consumer price index (CPI) for foods. An unexpected increase in regulated items prices came amid unanticipated increases in international fuel prices, on some utilities rates, and for regulated education prices. The decline in annual inflation excluding food and regulated items between December and March was in line with projections from January, though this included downward pressure from a significant reduction in telecommunications rates due to the imminent entry of a new operator. When controlling for the effects of this relative price change, inflation excluding food and regulated items exceeds levels forecast in the previous report. Within this indicator of core inflation, the CPI for goods (1.05%) accelerated due to a reversion of the effects of the VAT-free day in November, which was largely accounted for in February, and possibly by the transmission of a recent depreciation of the peso on domestic prices for certain items (electric and household appliances). For their part, services prices decelerated and showed the lowest rate of annual growth (0.89%) among the large consumer baskets in the CPI. Within the services basket, the annual change in rental prices continued to decline, while those services that continue to experience the most significant restrictions on returning to normal operations (tourism, cinemas, nightlife, etc.) continued to register significant price declines. As previously mentioned, telephone rates also fell significantly due to increased competition in the market. Total inflation is expected to continue to be affected by ample excesses in productive capacity for the remainder of 2021 and 2022, though less so than projected in January. As a result, convergence to the inflation target is now expected to be somewhat faster than estimated in the previous report, assuming the absence of significant additional outbreaks of COVID-19. The technical staff’s year-end inflation projections for 2021 and 2022 have increased, suggesting figures around 3% due largely to variation in food and regulated items prices. The projection for inflation excluding food and regulated items also increased, but remains below 3%. Price relief measures on indirect taxes implemented in 2020 are expected to lapse in the second quarter of 2021, generating a one-off effect on prices and temporarily affecting inflation excluding food and regulated items. However, indexation to low levels of past inflation, weak demand, and ample excess productive capacity are expected to keep core inflation below the target, near 2.3% at the end of 2021 (previously 2.1%). The reversion in 2021 of the effects of some price relief measures on utility rates from 2020 should lead to an increase in the CPI for regulated items in the second half of this year. Annual price changes are now expected to be higher than estimated in the January report due to an increased expected path for fuel prices and unanticipated increases in regulated education prices. The projection for the CPI for foods has increased compared to the previous report, taking into account certain factors that were not anticipated in January (a less favorable agricultural cycle, increased pressure from international prices, and transport costs). Given the above, year-end annual inflation for 2021 and 2022 is now expected to be 3% and 2.8%, respectively, which would be above projections from January (2.3% and 2,7%). For its part, expected inflation based on analyst surveys suggests year-end inflation in 2021 and 2022 of 2.8% and 3.1%, respectively. There remains significant uncertainty surrounding the inflation forecasts included in this report due to several factors: 1) the evolution of the pandemic; 2) the difficulty in evaluating the size and persistence of excess productive capacity; 3) the timing and manner in which price relief measures will lapse; and 4) the future behavior of food prices. Projected 2021 growth in foreign demand (4.4% to 5.2%) and the supposed average oil price (USD 53 to USD 61 per Brent benchmark barrel) were both revised upward. An increase in long-term international interest rates has been reflected in a depreciation of the peso and could result in relatively tighter external financial conditions for emerging market economies, including Colombia. Average growth among Colombia’s trade partners was greater than expected in the fourth quarter of 2020. This, together with a sizable fiscal stimulus approved in the United States and the onset of a massive global vaccination campaign, largely explains the projected increase in foreign demand growth in 2021. The resilience of the goods market in the face of global crisis and an expected normalization in international trade are additional factors. These considerations and the expected continuation of a gradual reduction of mobility restrictions abroad suggest that Colombia’s trade partners could grow on average by 5.2% in 2021 and around 3.4% in 2022. The improved prospects for global economic growth have led to an increase in current and expected oil prices. Production interruptions due to a heavy winter, reduced inventories, and increased supply restrictions instituted by producing countries have also contributed to the increase. Meanwhile, market forecasts and recent Federal Reserve pronouncements suggest that the benchmark interest rate in the U.S. will remain stable for the next two years. Nevertheless, a significant increase in public spending in the country has fostered expectations for greater growth and inflation, as well as increased uncertainty over the moment in which a normalization of monetary policy might begin. This has been reflected in an increase in long-term interest rates. In this context, emerging market economies in the region, including Colombia, have registered increases in sovereign risk premiums and long-term domestic interest rates, and a depreciation of local currencies against the dollar. Recent outbreaks of COVID-19 in several of these economies; limits on vaccine supply and the slow pace of immunization campaigns in some countries; a significant increase in public debt; and tensions between the United States and China, among other factors, all add to a high level of uncertainty surrounding interest rate spreads, external financing conditions, and the future performance of risk premiums. The impact that this environment could have on the exchange rate and on domestic financing conditions represent risks to the macroeconomic and monetary policy forecasts. Domestic financial conditions continue to favor recovery in economic activity. The transmission of reductions to the policy interest rate on credit rates has been significant. The banking portfolio continues to recover amid circumstances that have affected both the supply and demand for loans, and in which some credit risks have materialized. Preferential and ordinary commercial interest rates have fallen to a similar degree as the benchmark interest rate. As is generally the case, this transmission has come at a slower pace for consumer credit rates, and has been further delayed in the case of mortgage rates. Commercial credit levels stabilized above pre-pandemic levels in March, following an increase resulting from significant liquidity requirements for businesses in the second quarter of 2020. The consumer credit portfolio continued to recover and has now surpassed February 2020 levels, though overall growth in the portfolio remains low. At the same time, portfolio projections and default indicators have increased, and credit establishment earnings have come down. Despite this, credit disbursements continue to recover and solvency indicators remain well above regulatory minimums. 1.2 Monetary policy decision In its meetings in March and April the BDBR left the benchmark interest rate unchanged at 1.75%.

Lubricating oils for automotive engines have been incorporating important improvements in chemical properties to increase engine performance, reduce fuel consumption and vehicular emissions indices, in addition to increasing the time interval for changing the lubricant itself. The objective of this study is to investigate the vibrational behavior of the block and crankshaft an Otto cycle internal combustion engine operated with ethanol and gasoline fuel as a function of the viscosity and total base number (TBN) of the lubricant. The study consisted of instrumenting the block and the 1st and 5th fixed bearings of the crankshaft with accelerometers to measure the engine vibration intensity and operating the engine on a bench dynamometer in a specific test cycle. Each experiment lasted 600 hours and every 50 hours a block and crankshaft engine vibration level were measured and 100ml sample of lubricating oil was collected to check viscosity and TBN chemical lubricant's properties. The results show that the block and crankshaft engine vibration level increases with the time of use of the lubricating oil and that this increase is very significant when the oil viscosity an TBN chemical properties reaches the minimum value stipulated by the manufacturer lubricating oil. Semi-synthetic and synthetic lubricating oils have similar engine protection characteristics, but synthetic oil protects the engine for a longer period of time due to less degradation of viscosity an TBN chemical properties compared to semi-synthetic. Mineral lubricating oil presented protection for a very short test period, due to the rapid degradation of chemical properties and measurements showed an average increase of 20% of vibration engine running with mineral lubricating oil in relation synthetic and semi-synthetic oils. This research is important because it correlates the degradation of the lubricating oil with the engine vibration level and vibration problems in internal combustion engines produce premature wear on the internal components of the engine, which contributes to reduce the lifespan of the engine. This study also shows how is important to observe the correct application of automotive oils.