Volume 35 (04) July 2023

Walking is claimed as the best mode to school due to its benefits towards the environment and health. In the past, walking to school was a common mode. Nowadays, the safety and environmental issues, however, become decisive factors that prevent the parents to allow their children from walking. Despite its advantages, several investigations have shown that walking as a mode choice continues to suffer from narrow and weak foundations that impede to provide a unified identification of factors affecting the parents’ decision on walking as a mode choice. Addressing this issue, this article aims to provide a review of previous study on regards the factors affecting the parents’ decision to allow their children to walk to/from schools, the limitation of review is that the review was conducted on the published studies between 1995 and January 2019. The contribution identifies some factors affecting the parents’ decision about walking to school. It conceptualizes the relationship between different factors that affecting on parents’ decision. Out of 310 research articles 112 of them were the key of achieving the research objective as to element the founding that factors such as distance, safety, traffic, sidewalks, built environment, demography, and parents’ perception have a great influence on parents’ decision to allow their children to walk to-and-from school. The findings of this review can be used to offer a better deal with parents’ concern about their children to travel actively and safely to school.

Keywords : Commuting mode choice, distance, safety, built environment, parent’ perception, public transportation.

This paper gives a comparative analysis of different types of Multilevel Inverters with T-Type inverters. The principal aim of the work is to analyse the T-type multilevel inverter operation with different multilevel inverters such as DiodeClamped Multilevel Inverter, Flying Capacitor Multilevel Inverter and Cascaded H-bridge Multilevel Inverter. All the inverters are compared and their advantages, disadvantages and usages are specified. The inverter used in our work runs on the multilayer bidirectional DC-DC converter. This can be used in Renewable Energy Sources and Electric Vehicle applications. The proposed design includes two power switches with an additional capacitor to balance the currents of the multilayer T-type (MLI) capacitor during an entire drive pattern or fault circumstances. In this design, the big capacitors being electrolytic in T-type Multilevel Inverter has been exchanged with longer-lasting film capacitors due to the highfrequency cycle-by-cycle current security between CN and CP. The converter’s dimensions and weight would be lowered by 20% because of this topology, as the number of switches and the capacitors used for balancing is reduced in this proposed design. The simulation analysis for five-level conventional T-type inverter and proposed T-type inverter with capacitor voltage balancing is done. The line-to-line voltages, line currents, phase voltages, three-phase voltages, and voltage total harmonic distortions are compared for conventional T-type inverter and proposed T-type inverter with capacitor voltage balancing. The simulation results shows that the proposed T-type inverter gives better performance compared to conventional T-type multilevel inverter.

Keywords: Diode-Clamped Multilevel Inverter (DCMI), Flying Capacitor Multilevel Inverter(FCMI), Cascaded H-bridge Multilevel Inverter(CHMI), Total Harmonic Distortion (THD), T-type Multilevel Inverter, Capacitor Voltage Balance, Switching Losses.

The Malaysian Palm Oil Board (MPOB) has introduced an engine-powered palm oil harvesting tool called CANTAS that can double the conventional harvesting output. However, there are several issues that are affecting the endurance and comfort of the harvesters. This paper discusses the comparison in the context of ergonomics, performance, and ecconomics of a battery-powered CANTAS called CANTAS Elektro, which could overcome the issues of the engine-powered CANTAS. The prototype was tested in the laboratory and the field to investigate its ergonomic factors. Test results revealed that CANTAS Elektro was more ergonomic than CANTAS as the deflection, configuration, temperature, noise, and vibration levels of the former were 38%, 42%, 59.8%, 12.7%, and 45.8–65.2% less than those of the latter, respectively. The harvesting productivity increased by 26.5% from 5.63 to 7.04 t/day, with an estimated saving of operational cost of RM1013/machine/ yr. The take-home pay of workers was increased by 29% from RM81 to RM107/man-day, apart from other fringe benefits. It was proven that the battery-powered machine was more cost-effective than the engine-powered machine, in addition to other advantages such as being carbon emission-free, clean, easy to maintain, less complicated and easy to handle.

Keywords: Harvesting; palm-oil motorised cutter; harvesting tool; battery driven harvesting tool

Early pterygium screening is crucial to avoid blurred vision caused by cornea and pupil encroachment. However, medical assessment and conventional screening could be laborious and time-consuming to be implemented. This constraint seeks an advanced yet efficient automated pterygium screening to assist the current diagnostic method. Patch region-based anterior segment photographed images (ASPIs) focus the feature on a particular region of the pterygium growth. This work addresses the data limitation on deep neural network (DNN) processing with large-scale data requirements. It presents an automated pterygium classification of patch region-based ASPI using our previous re-establish network, “VggNet16wbn”, the VggNet16, with the addition of batch normalisation layer after each convolutional layer. During an image preprocessing step, the pterygium and nonpterygium tissue are extracted from ASPI, followed by the generation of a single and three-by-three image patch region-based on the size of the 85×85 dataset. Data preparation with 10-fold cross-validation has been conducted to ensure the data are well generalised to minimise the probability of underfitting and overfitting problems. The proposed experimental work has successfully classified the pterygium tissue with more than 99% accuracy, sensitivity, specificity, and precision using appropriate hyperparameters values. This work could be used as a baseline framework for pterygium classification using limited data processing.

Keywords: Anterior segment photographed image (ASPI); Automated pterygium screening; Patch region-based; Deep neural network (DNN); Pterygium classification

Storms and floods are frequent occurrences that can disrupt communities and harm ecosystems. An effective flood management plan requires a decision-making process that balances financial, social, and environmental benefits. This paper provides an overview of a study that applied a decision-making process using engineering analysis to determine the most effective approach in selecting the most effective flood mitigation measures. This study used hydrodynamic modelling to determine the effectiveness of proposed measures, such as the construction of a flood wall and river improvement works. The results showed that the combination of both measures could provide 100 ARI level protection, reducing the flood area from 6.11 km2 to 0.00 km2 areas without flooding. The study highlights the importance of considering financial, social, and environmental benefits in selecting effective flood mitigation measures.

Keywords: Cost benefit analysis; decision-making framework; economic analysis; flood management

Classroom communication is a very important and complex aspect in teaching and learning. The complexity of a communication process is attributed to a host of components that include the participants, messages, encoding, decoding, and transmission channels. Not much is currently known concerning classroom communication in the context of engineering education in Malaysian universities. This paper evaluates classroom communication of final-year students of the Electrical and Electronic engineering degree programs at Universiti Kebangsaan Malaysia. Four important aspects of classroom communication were investigated to understand student abilities and issues in classroom communication. One hundred and four students undertook the self-administered survey, yielding a response rate of 92.8%. The majority of the students exhibited good non-verbal communication practices, and scored favourably in the aspect of adapting the way they communicate to others. However, 42.3% of the respondents seemed to have difficulties to explain and express ideas confidently via classroom presentations. Additionally, 43 students (41.3%) appeared to be handicapped in participating actively in class discussions. Finally, at least 40 respondents (38.5%) reported difficulties to express ideas in English, but not to the extent of hindering them in participating in classroom discussions. Further studies are needed to uncover classroom communication issues in student learning among engineering students at Universiti Kebangsaan Malaysia.

Keywords: Engineering education; classroom communication; non-verbal communication; technical communication; soft skills

The social distancing among people is vital in minimizing spread of COVID-19 among community and can be effective in flattening the outbreak. This research work on developing a close contact proximity detection system among smartphone users and particularly of COVID-19 patient using Bluetooth signal to identify and analyze close contact proximity and social distancing from other anonymous smartphone user in his/her surrounding and to alert user if the social distancing is breached. The methodology used the Radio Signal Strength Indicator (RSSI) signal to analyze and estimate the proximity distance and duration of the individual’s exposure to other peoples in surrounding area. The overlap zone of 1-meter is used to indicate detection of closed contact proximity between users. Furthermore, the collected data can be used to do contact tracing that enable health official to identify the closed contact of infected patient systematically, faster and can ensure coverage of people that anonymously and not directly known to the COVID-19 patient. An encouraging result is obtained on the closed contact proximity detection which shown within the mobile apps. Furthermore, the performance of system for close contact proximity detection shown that indoor location has a good signal distribution compared to outdoor location.

Keywords: COVID-19 patient; close contact proximity detection system; social distancing; bluetooth signal

Engineering translations are dense with technical jargon and terms that necessitate linguistic and field expertise. The challenges arise from the requirement that the target texts be idiomatic and retain the same phrasing order, meaning, and nuances as the source text, which a layperson cannot translate directly. The Malay language is Malaysia’s official language. Because Malay is the official language in the governing and executive constitutions, the research instrument should be available in Malay. The purpose of this research is to translate from English to Malay a qualitative risk framework for solid waste engineering. On three psychometric scales, 26 items were translated using a back-translation method involving eight linguistic experts. The Malaysian Institute of Translation and Books (ITBM) provided the primary translation, which was then reviewed by a panel of experts as a secondary translation. Next, content validation on a 5-point Likert scale was conducted with five civil engineering field experts to assess instrument structure and reliability agreement. To represent the expert validation process, a descriptive analysis of mean score agreement was performed. The studies discovered deviation losses in forward (8.98%) and backward (17.95%) translation. The results also revealed experts produce accurate translations, particularly the equivalents of engineering expressions, acronyms, measurements, and terminology. Eventually, expert consensus on six aspects was achieved for 27.8/30 (92.7%) and affirmed that the framework is valid and thus applicable. This paper recommends that translation requires quality control, which comprises three processes: conversion to the target language, comparison, and reconciliation by subject matter experts.

Keywords : Civil engineering; risk framework; solid waste; qualitative translation

Rice is an important source of food for humans and holds higher importance, it grows on plants in a shell called a hull. To extract, the rice from its shells a rice milling machine is used. These processing machines are costly and not feasible for farmers to buy for their domestic purposes or for small-scale industries. For overcoming this problem an innovative and affordable rice mill is required, for small businesses. Not only the cost but also the machine parameters are much important. This paper is aimed to evaluate the performance of the designed small-sized model of the rice milling machine along with the analysis of the set parameters for the economic rice extraction from the hull without damaging the kernels. In the first step, a conceptual model in CAD was drawn including detailed specifications. In the second step, the design was evaluated and utilized to reproduce/ fabricate each component for a practical machine. Lastly, the machine was evaluated for its performance. Moreover, an automatic feeding system was also introduced as an innovation to reduce feeding labor and increase production. From the results, it was found that the automatic feeding system was reliable, moreover, the 3-horsepower motor was reduced to 2 horsepower for power saving. The cost of the machine was reduced from 80000Pkr to 55000Pkr. However, the rice processing speed was reduced to 100 kg/hour, from 200 kg/hour, which is aimed to be compensated via an automatic feeding mechanism.

Keywords: Automatic feeding, cost reduction, design innovation, milling machine, portable design

The application of electromagnetic signals in earthquake study has been applied by previous researchers through the monitoring of geomagnetic variations. The previous studies have revealed inconsistencies in the implementation of the diurnal variation ratio (DVR) method and the results were also found to be limited in specific events. This study sought to enhance the reliability of earthquake forecasting by implementing two different variants of the DVR method in investigating the magnetic responses prior to earthquakes (EQ). Global EQ events that occurred between 2000-2020 with magnitude above 5.0 were observed. The anomalies were detected as early as 60 days to 1 day prior to the EQ events for DVR using threshold value (Method 1), and 30 days to 15 days prior to the EQ events for DVR using the comparison with 1-year background geomagnetic data (Method 2). All geomagnetic N, E, and Z components showed anomalous behaviour during the quiet days but with temporal lags between the components. It can be concluded that Method 1 approach, yielded results with significantly more precursor presence than Method 2. The relationship of the geomagnetic variations with earthquake properties such as magnitude and focal depth showed higher rate of precursor presence in both the strong and mid-focus EQ. Future studies will be conducted to correlate geomagnetic variations with seismo-ionospheric response and physical ground movement prior to the events. The outcomes of this study will be able to provide insights of effective analysis for precursor study particularly in seismic hazard.

Keywords: Geomagnetic diurnal variations; earthquake precursor; SuperMAG database, diurnal variation ratio (DVR)

This study uses the artificial neural network and response surface methodology to develop two models for predicting the rheological properties, complex modulus (G*) and phase angle (δ) of bitumen-filler mastic. It also analyses and evaluates the accuracy of both models by determining the coefficient of determination (R2), mean squared error (MSE), and root mean squared error (RMSE). The prediction models use the G* and δ data from a previous study by researchers at the Nottingham Transportation Engineering Centre to determine three types of bitumen-filler mastic (limestone, cement and grit stone) with varying filler concentrations of 15, 35, 40 and 65%. The analysis shows that both models perform well in predicting the rheological properties of bitumen-filler mastic. A comparison of the two models shows that the artificial neural network (ANN) has higher accuracy than the response surface methodology model, with an R2 value exceeding 0.92. The results of the ANN achieve a higher R2 value and lower MSE and RMSE values. In summary, the performance of the artificial neural network model is better than the response surface methodology model, which uses the full quadratic, pure quadratic, linear and interaction mathematical methods.

Keywords: Artificial neural network, Response surface methodology, Complex modulus (G*), Phase angle (δ)

An Overlapping Grid Method (OGM) with Biquadratic Spline Interpolation in scattering technique was developed to solve the direct and inverse scattering issues. A two-dimensional (2D) numerical image model was used to analyze the accuracy of the proposed method in a direct scattering process. It was discovered that when the sub-grid, sx ∆ increased, the absolute error for the electric field amplitude will also increase. The results also discovered that as the grid size ratio increased, the absolute error of the amplitude Z E will also increase. The findings show that smaller grid spacing and a finer grid size can produce more accurate results. The Overlapping Grid Method (OGM) with Biquadratic Spline Interpolation was expanded by incorporating with Forward-Backward Time Stepping (FBTS) technique to solve inverse scattering issues. Homogenous embedded objects with a square and circular shape are used to validate the efficiency of the proposed method. The findings showed that the proposed numerical method could detect and reconstruct embedded objects in different shapes. The efficiency of the proposed method was examined by Mean Square Error (MSE) and normalizing the functional error. The findings revealed that the MSE of dielectric profiles for the proposed method were lower than the FDTD method in FBTS. The relative permittivity and conductivity profile differed by 27.06% and 20%, respectively. Hence, it was proven that the proposed method successfully solved a known drawback to the FDTD method and produced more accurate and efficient results.

Keywords: Overlapping Grid Method; Spline Interpolation; scattering technique; object reconstruction

In order to reduce energy and natural resource consumption during road construction, the sustainability concept needs to be seriously addressed. Oil Palm Fruit Ash (OPFA) is one of the by-products of palm oil production that are typically disposed of in landfills as a result of the growing number of plantations in Malaysia, particularly in Sarawak. Due to the fact that OPFA is known as biomass with pozzolanic qualities (siliceous material), this study was carried out to examine the applicability of OPFA with varying concentrations (0% – 40%) by weight as a modifier in bitumen grade 60/70. Based on the results of the laboratory testing, it was discovered that the modified bitumen provided greater resistance to rutting, temperature, and skid resistance on the bituminous mixture (AC20) compared to the control sample. The 40% OPFA modified samples had the greatest resilient modulus test value, measuring 10992 MPa at 25 °C and 2936 MPa at 40 °C, respectively. In addition, the combination containing 40% OPFA produced the lowest deformation value in the dynamic creep test, which was only 0.20mm, while producing 83.63 skid numbers in the skid resistance test. OPFA can be utilized as a binder modifier to improve the performance of bituminous mixture, which indirectly supports the sustainable development goals (SDGs) concept in road construction, as this study conclusively demonstrated.

Keywords: Sustainability; waste material; oil palm fruit ash; binder modifier; bituminous mixture

A “smart city” is one that makes use of info and comm technologies (ICTs) to increase the awareness, interaction, and effectiveness of city services and monitoring. It might be smart technology, smart design, smart mobility, smart utilities, smart housing, smart healthcare, smart transportation, smart lighting, smart phone detection, smart road, smart traffic management, and smart parking etc. The solicitation of smart cities will increase unexpectedly with the rapid increase in IoT infrastructure. Smart city idea notably going up to city lifecycle. The focal point of this paper is to present an intelligent parking system consuming a novel iOS app-based implementation for smart cities’ demands, which permits a driver to determine a parking lot and a vacant slot in that lot indoor a municipality. This paper additionally focuses on reducing the searching time for determining the parking lot using our proposed method, namely, the booking method. This, in short, lessens the gasoline deployment which in turn cuts carbon trails in the weather, as a way of life, additionally averting useless traveling via packed parking lots in a parking lot that can be useful in decreasing illegal parking and in a way help with the traffic jams we see in our city.

Keywords: iOS; smart parking; parking lot; booking method; cloud database

The solicitation of smart cities will increase unexpectedly with the rapid increase in IoT infrastructure. Smart City idea notably going up to city lifecycle. Parking is an important part of smart cities yet parking is a difficult process because there isn’t a good way to pay for it or find a spot in the existing system. The number of vehicles in our city is increasing day by day due to which there is an immediate need for a good parking system. The focal point of this paper is to manage parking lots by including dynamic costing methods incorporated in a novel iOS apps-based implementation for smart cities’ demands, which permits a user or driver to make an option for pricing the desired slot and booking the desired slot based on costing in that lot. That means, that developed iPark proposes innovative costing strategies that permit the making of additional parking profits and the rational ordering of parking transportation through parking lots. This paper additionally focuses on reducing the searching time for determining the parking lot using our proposed method, namely, the booking method. From the results, we can see that our proposed method increases profits as well as utilized resources properly compared to the existing methods.

Keywords: Dynamic Costing Methods; Static Costing Methods; iPark; Smart Billing; Parking Lot

Monoethylene glycol (MEG) or Ethylene Oxide is an important chemical in plastic and automotive industry as mixed ingredients or cooling liquid. It is produced from ethylene oxide via hydrolysis at 200ºC and 22 atm. The ratio of the ethylene oxide with water should be maintain at 1:20 to reduce the formation of diethylene glycol and higher homologs. Objective of this study is to predict a production of MEG using fuzzy logic. Others parameters such as level, temperature, composition and pressure are consider constant in this research as this study focusing on single input, single (SISO) output strategy. For fuzzy logic prediction, the type of model chosen is Mamdani with triangular membership function, input 1, input 2, and output which refer to error, feedback, and production of ethylene glycol respectively. 11 rules has been construct in this research. The rules may contain “AND” or “OR” conjunctions. The “error” represents the difference between the value feedback and the output. The results for fuzzy rules give highest product of MEG (6.91) at error of 0.102 and 0.8 of feedback. The gain of proportional, integral, and derivative are 0.2, 0.2, and 0.1 respectively.

Keywords: Fuzzy logic, MATLAB, MEG, Prediction

Small- and medium-sized manufacturing enterprises (SMEs) were confronted with a variety of difficulties due to the increasingly complex market environment, and many of them could not make enough profits to proceed with their manufacturing tasks. The objective of this study was to develop a model of risk management by integrating several risk tools at manufacturing companies. This study was also intended to improve the decision making by providing quantitative analysis at each step of risk management and improve lean practices. Risk quantitative analysis methods such as failure modes and effects analysis (FMEA) and multi-objective optimization on the basis of ratio analysis (MOORA) were applied in this study to identify the potential risks. Moreover, the risk assessment was used to categorize risks into different severity levels. The manufacturing data obtained from a case study was utilised to calculate the risk priority number (RPN). The risk mitigation actions were formulated to reduce the original RPN and the final RPN value decreased to a normal standard in the end. Overall, this study optimised the risk management of one case study SME and improved lean manufacturing practices. By establishing the risk identification model and applying common lean manufacturing concepts in reducing wastes at actual manufacturing processes, the manufacturing enterprise could manage to optimize the operations and increase the actual manufacturing productivity. The machining and assembly processes of diesel engines were optimized and improved with the decrease of RPN and the selection of the CK6150 CNC lathe that owns the highest MOORA assessment value.

Keywords: Lean manufacturing; SME; FMEA; MOORA; Risk identification

Navigation applications such as Google Maps and Waze fail to function at global positioning system (GPS) denied environments. This is typically the primary problem faced by mountain hikers who have lost their way in a dense forest or a dementia patient who has lost his/her way. Navigation applications fail to function at places without internet signal. Also, a dementia patient may not be able to recall his original destination, rendering the GPS useless.The development of a path tracking system which does not rely on GPS is therefore necessary in such a situation. The system should be capable of guiding a person to return back to his/her original starting point without the requirement of a GPS. In this paper, we present the development of a path tracking system which exploits the inertial measurement unit embedded in a mobile phone. Doing so, the use of the GPS can be evaded. The system that we have developed consists of 3 main functions, i.e. (i) path recording, (ii) path navigation, and (iii) map generation. An SQLite database is setup in this application for storing data. Java libraries such as GraphView and Canvas are implemented to perform observation on the data obtained from the sensors and also to map the route according to the data stored into the device. The validation results show that the accuracy of the system is beyond 90%. The results convincingly corroborate the reliability and feasibility of the system.

Keywords: Global Positioning System (GPS); Path tracking; Inertial Measurement Unit (IMU); Accelerometer; Geomagnetic field sensor; SQLite database; GraphView; Canvas

Vegetation plays an important role in the hydrodynamic behaviour of an open channel flow. This study attempted to investigate the flow characteristics of an emergent vegetated channel using Open-source Operations and Manipulation (OpenFOAM). InterFoam is an OpenFOAM solver used to model this simulation. It is one of the methods available to model free-flow surface flow. Results for flow velocity profile can be generated using ParaView software. This study used a constant inlet velocity of 0.0417 m/s. There are two sets of models including model L8 with a solid volume fraction (SVF) of 8% using 9 rigid dowels, and model 4S with SVF of 4% using 17 dowels within a 1.2 m2 study area. Dowels in L8 are arranged in linear formation compared to the 4S model in a staggered arrangement. The study found that in model 4S, the stem-scale vortices are developed individually after each dowel due to sparse staggered vegetation. Meanwhile, model 8L suggests oppositely the vortex is cramped from the closeness of the dowels. The shear layer is formed as the flow enters the vegetation patch at upstream and the instability causes the shear layer vortices between inside and outside the vegetation region. Both models agreed that as the flow moves downstream the vortices are greater and make the streamwise velocity region become slower. The vertical velocity profile acknowledges the shear layer patch-scale vortices have a greater influence on the flow of both models. The magnitude of turbulence intensity in lateral directions is bigger in model 4S than in model 8L. The influence of vortices shed by upstream cylinders has an increasing impact on the irregular shedding behaviour of downstream cylinders as plant density increases. In general, the TKE values of the Model 4S are higher than those of the Model 8L. Regardless of the solid volume percentage difference, the vegetation pattern between linear and staggered has an effect on the flow. Computational Fluid Dynamic (CFD) is indeed capable to solve complex hydrodynamic characteristics.

Keywords: OpenFOAM; Emergent vegetation; Flow; Turbulence intensity; Turbulent kinetic energy

Shared Prosperity Vision 2030 (WKB2030) is one of the Malaysian government’s initiatives to achieve the goals of a developed country by the year 2030. It is one of the motivational pillars that ought to underpin state-level policymaking and development strategies with the participation of all relevant professional professions. The geomatics engineering profession is one of the country’s core prospects and has contributed to the geomatics field in Malaysia, also responding to the call of WKB2030. Unfortunately, the digitalization process is moving too fast and adaptation to current technologies is crucial to stay relevant in the industry. As a result, this study highlighted the geomatics engineering direction through previous study trend identification and the compilation of the blueprint for WKB 2030 to ensure the geomatics engineering profession strives hard in adapting and contributing to national development. To empower the geomatics engineering ecosystem, various initiatives have been emphasized with the involvement of the geomatics engineering community in implementing new measures to enhance the field’s established services by leveraging innovations developed in the context of the Fourth Industrial Revolution (IR 4.0). Lastly, this manuscript will examine, from a geomatics engineering stance, how the geomatics field has adapted to recent technological breakthroughs in order to realize the WKB2030 objectives.

Keywords: WKB2030; geomatics engineering; geospatial; direction

Parking problem has become a big problem for us in daily life. Mainly in urban and city corporation area like mall, market etc. we face this problem more and finding space for parking here is very difficult. As a result, we spend a lot of time and energy. Finding a parking space has become a much more frustrating event for the driver or user. If the users or drivers do not get any parking space and park their vehicles randomly anywhere then the road will be jammed and the safety of the vehicles will be threatened. It is also the cause of many accidental incidents. It is the manual system that we usually see. We need a smart parking system that will play a role in creating the smart city of the future. We propose an iOS apps-based parking system to solve this problem of manual system. It allows users or drivers to find parking spaces and park their cars through mobile apps i.e., our developed iOS apps for smart parking. Then we do a comparative analysis of our system with the manual system with direct participation of users and see if our system is used then the existing problems will no longer exist.

Keywords: Ultrasonic Parking Sensor, User/Driver; IoT; Raspberry Pi; Cloud Database; iOS Apps