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Solid state drives, or SSDs, are now common storage devices. But rising popularity rarely means rising understanding. If you’re not quite sure how an SSD works, you’re not alone. Here we explain how flash memory, a.k.a. NAND memory, actually works, what the different “levels” of NAND mean, and how to get a good deal on an SSD today.

What is NAND memory?

Computer processors and memory are built from logic gates. These are the physical manifestation of the computer’s ability to process 1s and 0s. Based on their inputs, they provide certain outputs. Different kinds of gates process inputs differently. In very broad terms, the careful combination of these gates allow a computer to do everything from adding two numbers to recognizing photographs.

SSD memory is built from NAND gates, which are a type of logic gate. NAND stands for “not AND,” and it’s the inverse of the common “AND” logic gate.

How can a logic gate store information?

NAND gates have a special property that’s not shared by most types of logic gates. NAND gates can be used to create what’s called a flip-flop gate. This is a circuit made from two NAND gates wired together in a very specific way. As seen above, the output of each NAND gate is wired to the input of its partner.

This wiring allows for the storage of 1s and 0s over time and without power. So, with the proper wiring, NAND gates can create computer memory for one bit. Put a bunch of NAND gates together, and you can store a bunch of bits. And that’s what makes flash memory and, eventually, an SSD.

What is SLC, MLC, TLC, and QLC?

Flash storage is built on cells, which store bits. The most basic means of storage is a “single-level cell,” or SLC. These cells can be set to 0 or 1 to indicate on and off. These cells are fast and durable, but they don’t provide much storage. We need to store more than one bit per cell to increase that.

That’s where multi-level cells, or MLC, come in. These cells store two bits of information in one transistor by utilizing four levels of charge. For example, they might use 0v, 1v, 2v and 3v to represent 00, 01, 10, and 11 in binary. These cells fit more data but also require more precise techniques for storage and retrieval.

The newest SSDs are built on tri-level cells, or TLC, which allows each cell to store three bits. This requires even more precise fabrication, increasing cost and capacity at the expense of speed and reliability.

The next step is quad-level cells, or QLC. While Intel and Micron have developed a process for this, we aren’t likely to see mass adoption for years yet.

What is 3D NAND?

Early SSDs were fabricated like computer processors. They were created on a two-dimensional plane, and capacity and speed were increased by shrinking the transistors that made up the die. The more transistors you can fit on a die, the more data you can store. But unlike CPU transistors, SSD transistors can’t go much lower than 15nm. This is because, at that level, electrons can start leaking into nearby transistors, corrupting data.

To get around this limitation, manufacturers created 3D NAND. Here, transistors are also stacked on top of each other. This three-dimensional process, sometimes called V-NAND, allows up to sixty-four layers of transistors to occupy a single die. This increases storage possibilities by an order of magnitude.

The trade off is that 3D NAND requires extremely precise fabrication techniques to create the hyper-precise columns of transistors. This is especially important for MLC, TLC, and QLC type SSDs, which already require highly-precise fabrication to work properly. But that hasn’t stopped it from taking over the modern marketplace.

How it all comes together

Many fabs are putting out 3D TLC NAND drives, but there’s still significant available stock of MLC drives that are fast, moderately large, and suddenly very cheap. If you’re looking to score a bargain, now is the time to buy. It is a slightly older technology, but the main difference will be in storage size rather than performance. If there’s a bargain on a 3D MLC NAND drive that’s large enough for you, don’t hesitate to pounce.

As in all things electronic, a history of manufacturer reliability is extremely important. Cheap no-name drives might be made on older process nodes or with looser tolerances. They can also come from the leftovers of more discerning fabricators, selling you the just-functional-enough leftovers. Neither are a recipe for long-term success.

The next big revolution in SSD tech will come with massively larger capacity at the same or similar power levels. We can expect to see those roll out over the course of the next several years as foundries get experience with the techniques required for the new process design.

Also, check out the differences between SSD, HDD, and flash storage.

Image credit: flashdba, Cactus Tech

Alexander Fox

Alexander Fox is a tech and science writer based in Philadelphia, PA with one cat, three Macs and more USB cables than he could ever use.

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How Coalesce Works In Redshift?

Definition of Redshift coalesce

Redshift coalesce function will return the first not null value as result, coalesce function is built-in function of redshift. Coalesce function is work same as IFNULL function in SQL, this function will evaluates the argument from left to right and after finding the not null values it will not evaluate the remaining arguments. This function will accept the number of arguments but it will returns the first argument which was not null, if all the value are null then it will return the empty result set. This function is useful when we have returning the backup value.

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1) COALESCE (Value1, Value2,….,ValueN);

2) COALESCE (Argument1, Argument2,…., ArgumentN);

From table_name;


1) Value1 to ValueN – Any value which we have using with coalesce function in redshift. For multiple values coalesce function will return a first not-null value in result.

2) Coalesce – Coalesce is the function name in redshift which returns first not-null value as a result. Coalesce function is also known as NVL function in redshift.

3) Select – Select is used to fetch data from table by using a coalesce function in redshift. We can use multiple column or single column at one time to fetch data from table.

4) Argument 1 to Argument N – Argument is nothing but an integer value that we have passing with coalesce function in redshift. If suppose we have passing five argument with coalesce function and if first argument contains null value then coalesce function will return next not null value.

5) Column name – This is a column name of table which was we have using with coalesce function. If we want to fetch data from table using coalesce function in redshift then we need to pass column name.

6) Table name – This is nothing but the name of table which was we have using with coalesce function to retrieve first not-null value.

How coalesce works in Redshift?

Redshift coalesce function is used to return the first not null value from table column or argument list which was we have used in query.

This function will evaluates values or arguments from left to right to find the not-null value or argument. After finding first argument it will not evaluating the remaining argument from column or values which was used in query.

If our table column contains multiple null value but in result we have not required any null value at that time we have using coalesce function in redshift.

Coalesce function will returns the empty result when we have passing all the null values in our query.

Below example shows that coalesce function will returns the empty result when we have passing all the null values.


Select coalesce (NULL, NULL, NULL, NULL, NULL);

In above example, we can see that we have used all argument as null values. After checking all the null values result is showing the empty set.

After finding first not null value coalesce function will stop the query execution it will not check other argument or values.

Below example shows that after finding first not null value coalesce function will stop the query execution.

Select coalesce (NULL, NULL, 10, NULL, 50);

In above example, we can see that the result of argument list (NULL, NULL, 10, NULL, 50) is 10. After finding 10 coalesce function will not search the next value, it will not goes to search next 50 values which was not null. It will stop evaluation at 10 value.

Coalesce function is same function as NVL function which was used in big query. At the time of migrating the code into the redshift we need to rewrite this function into big query.

We can use single as well as multiple column while evaluating data using coalesce function in redshift.• If we want query which was return the result of null values of certain function same time we have using coalesce in redshift.

Coalesce function in redshift is also used with argument list which was we have using in our query. It will shows first not null values using argument list.


Below example shows coalesce in redshift are as follows.

1) Coalesce function with argument list –

Below example shows that coalesce function with argument list are as follows. We have passing the (NULL, NULL, 15, NULL, 20, NULL, 25, 30) argument list with coalesce function.

The result of the argument is 15. We can see that it will retrieves first not null value as 15 and skipping all the values which was comes after 15.


Select coalesce (NULL, NULL, 15, NULL, 20, NULL, 25, 30);

2) Coalesce function with single argument

Below example shows that coalesce function with single argument. We have passing only one argument as 50.

The result is below example is 50, because coalesce function has finds not null value in first argument.

Select coalesce (50);

3) Coalesce function using single column as argument list –

Below example shows that coalesce function using a single column as argument list are as follows.

We have using the start_date column from date table.


Select coalesce (start_date) from date1 order by 1;

4) Coalesce function using multiple column as argument list –

Below example shows that coalesce function using multiple column as argument list are as follows.

We have using the start_date and end_date column from date table.


Select coalesce (start_date, end_date) from date1 order by 1;


Redshift coalesce function is very useful to find the first not null value from column or argument list. If suppose all column value contains the not null value then coalesce function will returns the empty result. Coalesce function will stop execution after finding the first not null value.

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How It Works: The Next

There’s enough wind energy along our coastlines to power the country four times over, and the race is on to build the best offshore turbines to capture it. Manufacturers worldwide are experimenting with two techniques: ever-longer blades to harness more gusts, and simplified drivetrains (including new generators) that slash the need for costly repairs at sea. GE’s upcoming machine, slated to go online in 2012, will combine both into one package.

A Twist on Blades

The longer a turbine’s blades, the more wind it captures and the more electricity it creates. “If we could, we would just build infinitely longer blades,” Mercer says. “The problem is, blades get heavy and flexible.” That flexibility, coupled with the force from very high winds, can bend blades so much that they burden the machine or even smack the tower. So GE designed a blade that twists as it bends. It’s curved backward about eight feet, instead of extending straight out. When a gust pushes the tip up, the blade twists slightly around its curve—instantly angling itself so that it bears less of the gust’s brunt yet still captures a large part of its energy.

GE created lightweight 176-foot blades—about 40 percent longer than the average—with a more aerodynamic shape. The blades will attach to a drivetrain that does away with many of the moving parts, including the gearbox, that are prone to breakage and energy loss. A direct-drive mechanism replaces gears, and permanent magnets replace the electromagnets that require starter brushes, coils and power from the grid every time they fire up. The blades are now being tested in the Netherlands, and the drivetrain in Norway. Combining the two should result in a turbine that captures 25 percent more wind power than conventional models, so it can operate more often at its full four-megawatt potential—enough to power 1,000 homes.

Design Highlights on the Windmill

Generator: The 90-ton generator consists of a nearly 20-foot ring of magnets that spins to produce current. Its large diameter lets it create a lot of power when turning slowly, at the same 8 to 20 rpm as the blades, so it doesn’t need a gearbox to speed it up to the thousands of rpm most megawatt generators require. “Get rid of the gearbox, and now you don’t have to change the oil,” says GE engineer Gary Mercer.

Electrical Circuitry: Converters stabilize the current’s varying frequencies. Transformers boost voltage from 690 volts to more than 22,000, so current travels efficiently over long-distance lines.

Blades: Light, stiff carbon fiber replaces fiberglass at critical points in the blades, so they lose pounds and gain strength. A flat (rather than tapered) edge gives them a shape that increases lift.

How to Spin Power

1. Position the Blades Based on data from wind-direction sensors, a yaw-drive motor turns the nacelle to face the wind. A pitch controller rotates each blade around a bearing, setting it to the best angle for the wind speed.

2. Capture the Wind The three-bladed rotor spins in winds from 7 to 70 mph, sweeping twice the area of a football field. A 23-foot-long steel rotor shaft and two roller bearings transfer the mechanical energy to the generator.

3. Turn it into Electricity The shaft spins the generator’s neodymium magnets inside stationary copper coils, inducing current in the coils. Circuitry adjusts the frequencies and voltage of the current and sends it off to the grid.

Next-Gen Wind Turbine

GE OFFSHORE TURBINE Rotor Diameter:360 ft. Tower Height: 300 ft. Maximum Power: 4 Megawatts

How Outer Function Works In Numpy?

Introduction to NumPy Outer

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Outer() is one of the predefined functions of the Numpy library, and mainly, it’s used for vector and matrix calculations; its basic syntax is as follows below.

import numpy as first x=first.ones() y=first.linspace() z=first.outer(x,y) print (z)

Above basic Python code, we have imported the numpy packages in the Python script, and it has called the pre-defined methods of the package. The vector has rows and columns for all the dimensions, releasing both 2D and 3D vectors in matrix multiplications.

How outer Function works in NumPy?

In the Numpy library, the outer is the function or product of two coordinate vectors in the matrix calculations. We use more than one vector with dimensions like any variables, and their variables are calculated using the “x” multiplication operator for calculating matrix outputs. If suppose we use the tensor type of datas like a multidimensional array of numbers, then the outer function will give the tensor as a result. It is also known and defined as tensor algebras. The outer function is also known as the outer product, and the tensor is also referred to as the tensor product. The outer function used dot products, and Kronecker products also used standard matrix multiplications.

The Numpy arrays have used both single and multi-dimensional arrays if we can pass the Python list to the arrays method in single or one-dimensional arrays. And if we pass the list of lists packages in the arrays method in multi or two-dimensional arrays. The matrix array multiplication in every inner list and the outer lists becomes the rows and columns if the number of columns equals the number of elements in each inner list. When we use arrays in the Numpy, it has some default and important pre-defined methods, which are arrange(), zeros(), and ones(), etc, while creating the NumPy arrays. Also, if we use the arrays, it takes the arguments like start index, end index, and some linearly-spaced types of numbers that can be the specified ranges. The index values are different depending on the application requirement.

Examples of NumPy Outer

Here are the following examples as mentioned below.

Example #1 import numpy as np p = np.array([3, 6, 8], float) q = np.array([4, 7, 13], float) print("The Calculation of Matrixes and vectors are.") print("p:") print(p) print("q:") print(q) print("The Outer function used in the p and q are:") print(np.outer(p, q))


Example #2


import numpy as np p = np.ones(6) q = np.linspace(-5, 3, 7) r = np.outer(p, q) print (r) x = [5, 9] y = [2, 6, 4] z = np.outer(x, y) print(z)


Example #3 import numpy as np p = np.array([[4, 3, 2, 1, 16], [-7, 4, 3, 6, 15], [-5, 2, 19, 11, 26]]) y = [2, 6, 4] print(p[:3, :7]) print(p[:6,]) print(p[:,5]) print(A[:, 4:8]) z = np.outer(p, y) prPostint(z)


In the above three examples, we described the outer function in different areas, as well as the Numpy library has used many other different methods like slicer(), inner(), ones(), etc. If the user inputs must be entered in multiple areas simultaneously, the inputs are validated in both the front and back ends. Depending on the application requirements, the inputs can be in number formats such as integer, float, or decimal point. When using the Numpy packages, it becomes essential to validate user inputs due to their specific design for integer formats and utilization of arrays and vectors for matrix calculations.


In this article, we have discussed some important points regarding the Numpy packages and their method, especially in the outer() function. So in the latest and future technology purpose, these Numpy packages and their methods are an important part of the technology trends.

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How Boolean Type Works In Powershell?

Definition of PowerShell Boolean

PowerShell Boolean operators are $true and $false which mentions if any condition, action or expression output is true or false and that time $true and $false output returns as respectively, and sometimes Boolean operators are also treated as the 1 means True and 0 means false.

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Boolean type is the form of the output and its output is True or False but for the syntax, it uses the comparison and conditional operators to compare the two or multiple values.

And there are other syntaxes based on the commands and conditions as well. Which are shown in the examples.

How Boolean type works in PowerShell?

When evaluating the Boolean expression it compares the left side of the value to the right side of the value. If the value of the left side is equal to the value of the right side then it is evaluated true otherwise false as shown below.

"Hello" -eq "hello"


It depends on the condition we apply. For example, the above operator is not case sensitive. If we use the case-sensitive operator then the output will be false. For example,

"Hello" -ceq "hello"


In the Boolean type, 1 is treated as $true, and 0 is treated as $false. For example,

-not 0


In the above examples we have seen that the left side of the object is compared to the right side of the object in the -EQ operator but let evaluate the below expressions.

2 -eq $true


In the above example, the first is true but the second is false. So when the first example is true, its reverse should be also true but the Boolean operator doesn’t work that way. It works on the typecasting and the left side of the object type plays the main role here. In the first example, 2 is automatically type-casted to Boolean while in the second example, $true is type-casted to the integer as shown below.

[int]2 -eq [int]$true


Condition like IF/Else also uses the Boolean output. If the condition is true then it uses the ‘IF’ block, otherwise else block is executed. For example,

else{“5 is less than 6”}

In the above example, if the condition checks whether the expression is true or false and that is a Boolean value and based on it, the script executes the block.

Few commands also directly return the Boolean values like Test-Path, Test-Connection, etc.

Test-Path C:Temp10vms.csv


While Test-Connection, by default doesn’t produce the Boolean output but when we add -Quiet parameter, it produces the Boolean output.

Test-Connection chúng tôi -Count 2 -Quiet


Dollar + QuestionMark syntax ($?) also produces the Boolean output. It checks whether the last command run was successful or failed and it gives the output accordingly.




Let us discuss examples of PowerShell Boolean.

Example #1: Using Comparison Operators to check Boolean values.

10 -ge 11


With String objects,

“abc” -ne “abc”


Example #2: Using the cmdlets

Using those cmdlets which returns the output Boolean type. For example,

Test-Path command.

This command directly returns the Boolean value based on the path existence. For example,

Test-Path C:Temp


Test-Connection command.

Some command returns the value but not the Boolean value but they support parameter which returns the Boolean value. For example, the Test-Connection command uses -Quiet parameter to return a Boolean value.

Test-Connection chúng tôi -Count 2 -Quiet




Example #3: Commands without supported Boolean output parameter

Some commands don’t support the output which has true or the false value as the output and in that case, we can use those commands inside the IF/else condition to handle the Boolean output.



You can also use the Where block after a pipeline to evaluate if the output is true or false. For example,



In the above example, if the process doesn’t exist, it produces the output false and executes the else condition. Otherwise, the true output and will execute the IF condition.

Example #4: Boolean type output for multiple conditions

When there are multiple conditions used, the output will be as below.

-And will check if both the conditions are true then the output is True, otherwise False.

-OR will check if any of the condition is true then the output is True, otherwise False.

(6 -lt 5) -or (4 -gt 5)



Boolean types (True and False) are very useful while working with the scripts. While writing scripts, programmers need to evaluate the previous output and moves to the next commands if they are true or false. It also helps to create a flow chart properly for scripts.

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Defintion, Types, Example, How To Works?

What is Equity Financing

Equity financing is a process of raising capital by selling shares of the Company to the public, institutional investors, or financial Institutions.

Equity financing could be the perfect solution for you. It allows you to raise capital without debt by selling a portion of your business to investors. Here we provide examples of the types of equity financing available to you.

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Example of Equity Financing

An Entrepreneur started the company ABC with an initial capital of $ 10,000. At the start of the Company, he owns 100% of the equity in the Company. After a few initial years of starting, he is seeking new funds for the growth of the Company. He sells 50% of the equity of the Company at a valuation of $ 100,000. A venture capitalist or an angel investor will receive 50% equity in the Company by investing $ 50,000, and the entrepreneur’s stake will be reduced to 50%. However, he invested only $ 10,000 in the Company at the beginning.

Thus, Equity financing and the amount of stake each investor owns depends on the time and valuation of investments in the Company.

Types of Equity Financing

A Company can have different classes of shares; Equity financing does not only involve financing by common equity but through other mediums as well:

The Companies issue different classes of shares, usually large enterprises:

Class A shares: Investors get ownership, i.e., voting rights and dividend.

Class B shares: Investors get ownership (voting rights) but no dividend.

Preference shares: Investors receive a dividend (in some cases higher or guaranteed dividend) but no ownership.

Differential voting rights shares: Investors get differential voting rights, i.e., 2 shares owned by the investor will get 1 vote, and to compensate for this differential voting right, they receive a higher dividend than the common equity investors.

Sources of Equity Financing

When a new business starts, the owner invests the funds by selling his personal assets like land and property or cash assets. However, as the business grows and the need for financing increases, the funds are taken from external sources.

Various investors at different stages of the Company’s growth investments in the Company, and are mentioned below:

1. Angel Investors

Angel investors are typically the first investors apart from the business owner or founder. They are usually wealthy individuals and friends/family of the business owner. They provide financial backing at an early stage of the business at favorable terms and do not usually get involved in the management of the business. Angel investors generally take out their investments at higher returns once the Company seeks funds from venture capitalists.

2. Venture Capitalists 3. Retail Investors/IPOs 4. Crowdfunding

Crowdfunding is another way. Companies can raise funds from a group of investors in small amounts. Each investor invests a small amount in the business through a crowdfunding campaign the Company runs. The investors are generally a group of angel investors who believe in the product and the founders of the Company and would like to fund the initial setup of the business.


1. Companies seeking will typically create a business plan that outlines their goals and objectives.

2. Companies will then identify potential investors and present their plans.

3. Investors will evaluate the company’s plan and decide whether to invest.

4. If the investors agree to invest, they will provide the company with capital in exchange for equity.

Advantages of Equity Financing

The company does not have enough cash, collateral, or resources to raise funds from debt financing; hence equity financing is a good source of funds for the entrepreneur as the investors would take the risk of the business along with the founders.

Investors get ownership of the Company. They get better returns than other investment vehicles, either from increased share prices or dividends paid by the Company.

Loss of control: As the Company adds new investors, the founders’ reduced shareholding may lead to a potential conflict of interest and loss of control of their own Company. The active involvement of investors in the management of the Company may also create conflicts in the way of doing business.

Time and effort: Potential investors spend a lot of time in the Company’s due diligence before investing. They look for a business plan, sales and profit forecasting, and market conditions and must ensure their investment will be safe, secure, and profitable. Thus, it is time-consuming for entrepreneurs who are out seeking funds and also focussing on their business.


Equity financing is a mode of financing for the Company where it takes funds from the investors by selling shares. The Company can issue a different variety of shares to different investors. However, investors understand that such investments do not offer fixed returns like debt financing, where they borrow funds for a stipulated time and at predefined interest rates.


Q: What are the different types?

A: The different types of equity financing include venture capital, angel investors, and public offerings.

Q: What are the benefits of equity financing?

A: This can benefit long-term growth, allowing companies to access capital without debt.

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