Showing posts with label Mechanical Engineering. Show all posts
Showing posts with label Mechanical Engineering. Show all posts

T mobile!



Just a corny title to seduce all you avid readers to a very fascinating science concept. Flight dynamics and ship motion control work on the principle of pitch ,yaw and roll. Part of writing this blog is also to refresh my own memory about these three movements.

The image says it all.According to the above movements the ship heaves,sways and sways.It is common usage to use these three words to describe motion but one should notice each motion is completely different from the other.
One of the famous companies that does specialize in ship motion controls is NAIAD dynamics.One of their important products is the T foil. Ship and yacht manufacturers know that the final hull design and the ships balance depends a lot on design of the T foil.Just as the tail fin of an aeroplane is crucial to the extent of pitch the aircraft is subjected to,in the same way T foil has a substantial impact on the ship's stability.

Yacht racers take a particular interest in the shape and design of the t foil as this reduces the drag much considerably than a normal hull driven one.Wave pattern does not have any influence on the foil's ability to steer the course.Upwind , downwind directions and a wind greater than 12 knots still does not make a normal boat faster than a t foil rudder installed one.

This brings me to the question -how fast can it go?
Realizing the practical limitations considering drag among various other conditions one needs to find the optimum design to maximize performance



The figure above shows the maximum stress(red) at the edge. This stress might vary depending on the angle of attack and also on the size of the ship and the velocity of travel.Lesser stress region does not necessarily mean the foil is maximizing its performance.Its primary function is to minimize drag and reduce pitch and roll motions.

NAIAD dynamics customize these T foils which is important as foil's performance is highly affected by external factors and hence design of the same should be in accordance with this.The company also manufactures retractable foils.Retractable ones are not a bad idea since it can facilitate better performance only when the need arises thus increasing its functional life. Composite materials would be the ideal material for the foil mainly due to its low cost and light weight.
The greed for better performance will surely nuture better foil designs in the years to come.
Behold the future!


Dam these fish!

When ever man finds a solution to one problem he inadvertently creates another problem. Automotives increased efficiency of human life ,sped up daily life but all at the cost of our environment.The demand for space and new townships is turning the earth into a concrete jungle. No doubt humans have taken nature for granted and if this continues we might have to hunt for a 'Pandora'.


We are just unable to strike a balance between human development and nature conservation; One such example is that of effects of dams on marine life. When dams are constructed, they instantly alter the body of water they are installed in. In many instances, dams are constructed to control the flow of water. However, changing currents have an effect on the aquatic ecosystem, and usually on the wider environment in general.

The first thing to be affected by a dam is the flow of sediment, which is usually picked up along banks and stream beds, and carried downstream. Sediment collects behind dams, rather than continuing to flow out with the river, and as a result, the bed below the dam eventually becomes rocky and gnarled clean of sediment. Aquatic plants are unable to thrive. The nutrients in the sediment that nourish the fish and other aquatic life are no longer available, sometimes causing extinction in large numbers.

The most obvious impact that a dam has on fish is that it obstructs migration. For some fish species, such as salmon, which spawn in rivers and then swim out to sea, this can be devastating. For others, being unable to pass the dams means that there is not as much species diversity. Many dams in the latter part of the 20th century were built with fish ladders and other modifications that were designed to allow the passage of fish. But many fish are unable to use the ladders, or they die in the machinery of the dam. This has a profound impact on fish populations.

This decrease in the rate of migration also exposes sensitive fish species to predators that may lurk in slower flowing water. In the case of salmon, navigating multiple dams and contending with predators also affects the internal biological changes that allow them to switch from being freshwater fish to saltwater fish.

Water quality directly behind dams is also affected because dams tend to collect pollutants along with sediment, which must be released and controlled in some way. Especially in the case of deep dams, thermal stratification or a stagnant heat state develops because there is no current to mix the water. As a result, the deeper water is very cold and has poor oxygen circulation, while the surface water is warmer than usual. When colder deep water is released from dams, it can cause serious problems downstream for fish and other aquatic life due to its poor oxygenation and due to the toxins it may carry.

Legislators in California and Portland face a unique conundrum of their own. Since fishing industry is very much a part of their community's needs in addition to the moral responsibility of protecting marine life, one does not want to be on the wrong side of environmentalists among others and support construction of dams. On the other hand though, the states need to meet up the increasing demand of power, and dams are its biggest source.

California is blessed with miles and miles of rivers and most of them are harnessed by dams impacting the substantial population of wild trout and steelhead population. Many of the licenses come up for renewal and the environmentalists are faced with a golden opportunity to press upon this problem engaging the latest technologies to improve the fish's "house".

In Portland, Obama has tried to pursue a middle path envisaging the construction of new dams as well as adopting an "adaptive management implementation plan" which comes up with a series of contingency plans to protect the ecosystem should anything go wrong. Critics have panned this "insurance plan for the fish" as an eyewash as it advocates removal of dams as a last resort. Politics aside, both parties agree on the immediate need to resolve this issue as not only the fish population hangs in the balance but also the human population depends on the fish for a living.

Creating a dynamic flow within the river may be the only way to prevent stratification. Better technologies and innovative ways to maintain the nature and human balance would certainly be appreciated. The administration has to again pursue alternate means of developing power so that demand for more dams is nullified. It is a commonly known fact that it is impossible to keep everyone happy, but the challenge is to find a mutually beneficial solution so that the interdependency of nature and the human race is not at stake.

The wireless heart!

Many of us have heard of a pacemaker, right? One has heard numerous cases when the pacemaker failed and the patient was not aware of it and then suffered a stroke. For all those who are ignorant about it, pacemaker is a medical device wherein electrodes are in contact with the heart muscles. On detecting abnormal heart beats the pacemaker delivers electrical impulses through the electrodes thus bringing the heart to normal. A defibrillator also works on the same lines of the pacemaker but isn't pacemaker still an electronic device which obviously has a limited operational time and failure of any one of the small electrical components could cost a life?


One effective technology which could alert the person or his/her physician of the status of his/her pacemaker or defibrillator could be of immense use to persons vulnerable to sudden cardiac arrest.

Medtronic Inc. were one of the first to develop a smart implantable device which uses wireless telemetry, micro controllers, modems and internet technology to analyse heart rhythms, deliver shocks and send information to physicians -all without the aid of the patient.

One of the bigger challenges Medtronic engineers faced were transmission of signals without interference. RF signals were originally considered but replaced by a less known frequency band called MICS(medical implant communications service)-bandwidth of 402-405 mhz. Previously used for weather balloons and other meteorological aids, the MICS band offers the advantage of virtually no interference. Low interference translates to more effective use of power, because data need not be re send. A table top box which can receive these signals through an antenna was set up.

But still the data needs to be analysed and so Medtronic in collaboration with software giants like Microsoft developed a system known as CareLink Network which enables physicians to receive and analyze the data through the internet. If patients can keep in touch with their physicians from any part of the world this would be nothing short of a miracle. If the patient is sleeping or if he or she is not aware of atrial arrhythmia(irregular hear beats) the doctor is made of aware of it and he could treat them with the right drugs and possibly prevent a stroke which is the main purpose.

Although the initial tests and results are favorable,this device is not tried and tested. As the technology is in its infant stage and taking into account the economical viability of this machine, one can forsee the continuos use only in the distant future.The optimists are backing it as a medical technological breakthrough. How effective is it,only time would tell.

For the millions of people who might find this product of great use, it is a reassuring fact for them to know that their heart is in safe hands.

As they say , " A stitch in time saves nine".

Ocean Power!

The world is in the midst of an energy crisis.The craving for alternate sources of power has forced many governments across the world to provide funding for the same. In this era of depleting natural resources, wind power seems to garner a lot of interest.

Focussing on wind energy, one needs to impress upon this source's vast potentials. It is estimated that this energy source would provide 10 to 15 percent of the world's energy requirements in future.

U.S.A has vast amounts of land to install wind turbines or mills but what about smaller countries. How can they make optimum use of this energy for their needs? Smaller countries with large coastlines have a distinct advantage in that they can harness wind energy through the ocean. Off shore wind turbines installed in oceans is a relatively new field as compared to farm wind turbine. Wind farms on land can hinder the nearby residents and sensitive wild life as a result of their noise. Winds over the ocean are generally stronger.Why not move all the turbines to offshore areas?

Such is the demand for energy that the world would require both offshore and on shore wind farms.Also,wind farms provide significant economic development in the form of tax revenue to hard pressed rural communities and rent payments to farmers. Hence the on shore wind farms are also here to stay.

Off shore wind farms are not without its challenges.Much research needs to be done on the effects of wind farms on the ecological balance in the sea. One cannot compromise one part of nature for another. Recent articles state the efforts of NASA's QuikSCAT satellite which help in pointing out the different ocean areas where winds are most likely to produce energy. The different maps aid the scientists in developing new wind farms. A wind farm also demands a large coastline and shallow water. So countries which have these advantages need to be proactive and start researching more. Many countries in Europe have proposed many off shore wind farms as a result of their limited land space.

Wind farm installation cost increases with water depth and wave height and also cost increases as the wind farms are farther out to the sea. What about interference with shipping, fishing, and marine life? Well,wind farms would not find a place in busy shipping routes. In case of rough weather when ships are forced to change route, every wind turbine is equipped with a radar which gives out a warning signal to the ship. Not much evidence is there to support the fact that wind farms have an adverse effect on fishing. On the contrary, wind farms help in protecting the fishing industry. Many environmental groups believe that wind farms will provide welcome sanctuary for fish spawning as well as refuge from intense fishing activity.Wind turbines are also built in order to sustain the extreme wind conditions in case of storms at sea. If the wind speed crosses 50mph,the turbine automatically shuts down in order to avoid failure. Although construction of wind farms may cause disturbance to the marine life,it would last for a limited time of six months. During the operational period research shows the frequency of the sound of the wind turbine is too low to be heard by the marine life and hence would not cause any hindrance.

Overall,wind energy especially off shore wind farms promise much to the world in way of an efficient source of energy to support our planet.

The more we learn to save the better we can live.

As was quoted in Times once -"Don't blow it-good planets are hard to find".

Rocket man!



I never think of the future - it comes soon enough-Albert Einstein.

But "how soon?" is the inevitable question. Could we go to work like George Jetson in his little spaceship. Ah!The indefatigable thirst for knowledge of mankind can bring this day very close. Reading about different inventions and research in recent times,I came across an article about Mr. Nino Amarena, an engineer from Argentina who specializes in making rockets.Well, they are miniature sized jet packs which can be worn like a backpack and with a push of a button you take off. If it was that easy, nobody would have bought a Toyota Prius!OOPS! No offence!

Mr. Amarena has been working on the rocket pack for over a decade and has seen reasonable success, I would say. One needs to consider the enormous challenges in this nascent area. In the 1960's Wendell Moore who invented the rocketbelt for Bell Aerosystems stopped flying after shattering his knee in a crash. Understandably few individuals have taken upon them to venture into this. Nino Amarena's logic is simple "create more thrust than the weight". He calls his jetpacks thunderpacks that are capable for a maximum 45 second flight.The thunderpack's gas generator decomposes hydrogen peroxide and then uses an inert gas like nitrogen to push the exhaust out at high pressure.Catalyzing hyydrogen peroxide results in an exhaust gas mixture of superheated steam and oxygen.The inert gas stored above the fuel blows down the exhaust creating the required thrust of around 380-400lb.One uses the controls in the handle to orient the exhaust nozzle by which one can manuever around while off the ground.

Many interesting features about the rocketbelt,one of them being the use of "jetavators". These are small rings mounted on the exit areas of the nozzles which work similar to that of ailerons in aeroplanes. When the jetavator on the left nozzle moves downward while on the right moves upward,i creates a push in one direction and allows the pilot to yaw.

The rocketbelt efficiency can be increased by two ways-1.) reduce the weight of the pack and 2.) increase fuel capacity.Obviously the single most drawback of the rocketbelt is its short flight time. At a price of over 100K a minute flight does not seem that attractive. Thunderbolt systems -Nino's company has been pursuing a different chemical composition to sustain the chemical reaction. Either the fuel capacity of the pack should be increased at the same time not compromising on the weight or the fuel should produce the required exhaust for an extended period of flight. In one of the videos they have demonstrated how the pack works.It does give the required thrust to lift off the ground but not good enough. In the long run, the company could be focussing on achieving more elevation and to sustain that elevation. As of now it might sound to some as a crazy science experiment, but Nino believes it can change the world of human travel in the years to come.The military could find some use in this technology and considering the advantage it could have added for Haiti relief and rescue efforts the rocket man is here to stay.

It is that man's incessant fixation of 'mankind to fly like a bird' that has and will propel him to heights which even some of his fellowmen dismissed as impossible.Encouragement fuels desire!



Blogger Template by Blogcrowds