与其他优化算法一样,种群个体在搜索空间内随机初始化。
INFO使用基于均值的规则(MeanRule)更新向量的位置,这是从一组随机向量的加权均值中提取的。此外,为了提高全局搜索能力,在更新规则算子中加入了收敛加速部分(CA)。更新规则的主要公式定义为:
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(1)
\begin{array}{l} z 1_{l}^{g}=\left\{\begin{array}{ll} x_{l}^{g}+\sigma \times \text { MeanRules }+\text { randn } \times \frac{x_{b s}-x_{a 1}^{g}}{f\left(x_{b s}\right)-f\left(x_{a 1}^{g}\right)+1}, & \text { rand }<0.5 \\ x_{b s}+\sigma \times \text { MeanRules }+\operatorname{randn} \times \frac{x_{a 2}^{g}-x_{a 3}^{g}}{f\left(x_{a 2}^{g}\right)-f\left(x_{a 3}^{g}\right)+1}, & \text { rand } \geq 0.5 \end{array}\right. \\ z 2_{l}^{g}=\left\{\begin{array}{ll} x_{b s}+\sigma \times \text { MeanRule }+\operatorname{randn} \times \frac{x_{a 1}^{g}-x_{b}^{g}}{f\left(x_{a 1}^{g}\right)-f\left(x_{a 2}^{g}\right)+1}, & \text { rand }<0.5 \\ x_{b t}+\sigma \times \text { MeanRule }+\operatorname{randn} \times \frac{x_{a 1}^{g}-x_{a 2}^{g}}{f\left(x_{a 1}^{g}\right)-f\left(x_{a 2}^{g}\right)+1}, & \text { rand } \geq 0.5 \end{array}\right. \end{array} \tag{1}
z1lg=⎩⎨⎧xlg+σ× MeanRules + randn ×f(xbs)−f(xa1g)+1xbs−xa1g,xbs+σ× MeanRules +randn×f(xa2g)−f(xa3g)+1xa2g−xa3g, rand <0.5 rand ≥0.5z2lg=⎩⎨⎧xbs+σ× MeanRule +randn×f(xa1g)−f(xa2g)+1xa1g−xbg,xbt+σ× MeanRule +randn×f(xa1g)−f(xa2g)+1xa1g−xa2g, rand <0.5 rand ≥0.5(1)
其中,
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z1lg和
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z2lg为第
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\sigma
σ为向量缩放率,通过式(2)计算所得;
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[1,NP]
[1,NP]中随机选择的不同整数;
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randn是一个标准正态分布随机值。应注意的是,在式(2)中,
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α可以根据式(2.1)中定义的指数函数进行更新。
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\sigma = 2\alpha\times rand-\alpha \tag{2}
σ=2α×rand−α(2)
α = 2 × exp ( − 4 g M a x g ) (2.1) \alpha=2\times \text{exp}(-4\frac{g}{Maxg})\tag{2.1} α=2×exp(−4Maxgg)(2.1)
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MeanRule
MeanRule定义如下:
MeanRule
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\text { MeanRule }=r \times W M 1_{l}^{g}+(1-r) \times W M 2_{l}^{g}, l=1,2, \cdots, N P \tag{3}
MeanRule =r×WM1lg+(1−r)×WM2lg,l=1,2,⋯,NP(3)
其中,
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r是 [0,0.5]之间的随机数;
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WM1lg和
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WM2lg定义如下:
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W M 1_{l}^{g}=\delta \times \frac{w_{1}\left(x_{a 1}-x_{a 2}\right)+w_{2}\left(x_{a 1}-x_{a 3}\right)+w_{3}\left(x_{a 2}-x_{a 3}\right)}{w_{1}+w_{2}+w_{3}+\varepsilon}+\varepsilon \times \operatorname{rand}, l=1,2, \cdots, N P \tag{3.1}
WM1lg=δ×w1+w2+w3+εw1(xa1−xa2)+w2(xa1−xa3)+w3(xa2−xa3)+ε×rand,l=1,2,⋯,NP(3.1)
其中:
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w_{1}=\cos \left(\left(f\left(x_{a 1}\right)-f\left(x_{a 2}\right)\right)+\pi\right) \times \exp \left(-\frac{f\left(x_{a 1}\right)-f\left(x_{a 2}\right)}{\omega}\right) \tag{3.2}
w1=cos((f(xa1)−f(xa2))+π)×exp(−ωf(xa1)−f(xa2))(3.2)
w 2 = cos ( ( f ( x a 1 ) − f ( x a 3 ) ) + π ) × exp ( − f ( x a 1 ) − f ( x a 3 ) ω ) (3.3) w_{2}=\cos \left(\left(f\left(x_{a 1}\right)-f\left(x_{a 3}\right)\right)+\pi\right) \times \exp \left(-\frac{f\left(x_{a 1}\right)-f\left(x_{a 3}\right)}{\omega}\right) \tag{3.3} w2=cos((f(xa1)−f(xa3))+π)×exp(−ωf(xa1)−f(xa3))(3.3)
w 3 = cos ( ( f ( x a 2 ) − f ( x a 3 ) ) + π ) × exp ( − f ( x a 2 ) − f ( x a 3 ) ω ) (3.4) w_{3}=\cos \left(\left(f\left(x_{a 2}\right)-f\left(x_{a 3}\right)\right)+\pi\right) \times \exp \left(-\frac{f\left(x_{a 2}\right)-f\left(x_{a 3}\right)}{\omega}\right) \tag{3.4} w3=cos((f(xa2)−f(xa3))+π)×exp(−ωf(xa2)−f(xa3))(3.4)
ω = max ( f ( x a 1 ) , f ( x a 2 ) , f ( x a 3 ) ) (3.5) \omega=\max \left(f\left(x_{a 1}\right), f\left(x_{a 2}\right), f\left(x_{a 3}\right)\right) \tag{3.5} ω=max(f(xa1),f(xa2),f(xa3))(3.5)
W M 2 l g = δ × w 1 ( x b s − x b t ) + w 2 ( x b s − x w s ) + w 3 ( x b t − x w s ) w 1 + w 2 + w 3 + ε + ε × rand , l = 1 , 2 , ⋯ , N P (3.6) W M 2_{l}^{g}=\delta \times \frac{w_{1}\left(x_{b s}-x_{b t}\right)+w_{2}\left(x_{b s}-x_{w s}\right)+w_{3}\left(x_{b t}-x_{w s}\right)}{w_{1}+w_{2}+w_{3}+\varepsilon}+\varepsilon \times \operatorname{rand}, l=1,2, \cdots, N P \tag{3.6} WM2lg=δ×w1+w2+w3+εw1(xbs−xbt)+w2(xbs−xws)+w3(xbt−xws)+ε×rand,l=1,2,⋯,NP(3.6)
其中:
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w_1=cos((f(x_{bs})-f(x_{bt}))+\pi)\times \text{exp}(-\frac{f(x_{bs})-f(x_{bt})}{w})\tag{3.7}
w1=cos((f(xbs)−f(xbt))+π)×exp(−wf(xbs)−f(xbt))(3.7)
w 2 = c o s ( ( f ( x b s ) − f ( x w s ) ) + π ) × exp ( − f ( x b s ) − f ( x w s ) w ) (3.8) w_2=cos((f(x_{bs})-f(x_{ws}))+\pi)\times \text{exp}(-\frac{f(x_{bs})-f(x_{ws})}{w})\tag{3.8} w2=cos((f(xbs)−f(xws))+π)×exp(−wf(xbs)−f(xws))(3.8)
w 3 = c o s ( ( f ( x b t ) − f ( x w s ) ) + π ) × exp ( − f ( x b t ) − f ( x w s ) w ) (3.9) w_3=cos((f(x_{bt})-f(x_{ws}))+\pi)\times \text{exp}(-\frac{f(x_{bt})-f(x_{ws})}{w})\tag{3.9} w3=cos((f(xbt)−f(xws))+π)×exp(−wf(xbt)−f(xws))(3.9)
w = f ( x w s ) (3.10) w=f(x_{ws}) \tag{3.10} w=f(xws)(3.10)
δ = 2 β × r a n d − β (3.11) \delta =2\beta\times rand-\beta \tag{3.11} δ=2β×rand−β(3.11)
β = α = 2 × exp ( − 4 g M a x g ) (3.12) \beta=\alpha=2\times\text{exp}(-4\frac{g}{Maxg})\tag{3.12} β=α=2×exp(−4Maxgg)(3.12)
其中, w 1 , w 2 , w 3 w_1,w_2,w_3 w1,w2,w3是三个加权函数,用于计算向量的加权平均值,有利于算法在解空间中全局搜索; x b s , x b t , x w s x_{bs},x_{bt},x_{ws} xbs,xbt,xws 分别是第 g g g代种群中最优、次优和最差的解向量。事实上,这些解向量是在每次迭代时对种群向量进行排序后确定的。
根据式(5),INFO将前一阶段中计算的两个向量
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rand<0.5的向量
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(ulg)相结合,生成新向量。事实上,该算子用于提升局部搜索能力,以提供一个新的更好的向量。
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u_l^g=\begin{cases} \begin{cases} z1_l^g+\mu|z1_l^g-z2_l^g|,rand1<0.5\&\&rand2<0.5\\ z2_l^g+\mu|z1_l^g-z2_l^g|,rand1<0.5\&\&rand2 \geq0.5 \end{cases}\\ x_l^g,rand1<0.5 \end{cases}\tag{4}
ulg=⎩⎪⎨⎪⎧{z1lg+μ∣z1lg−z2lg∣,rand1<0.5&&rand2<0.5z2lg+μ∣z1lg−z2lg∣,rand1<0.5&&rand2≥0.5xlg,rand1<0.5(4)
其中,
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μ=0.05×randn
INFO使用局部搜索阶段来防止陷入局部最优解。根据该算子,如果
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rand<0.5,则可以围绕生成一个新的向量,其中是[0,1]中的随机值。
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u_l^g=\begin{cases} x_{bs}+randn\times(MeanRule+randn\times(x_{bs}^g-x_{a1}^g)),rand1<0.5\&\& rand2<0.5\\ x_{rnd}+randn\times(MeanRule+randn\times(v_1\times x_{bs}-v_2\times x_{rnd})),rand1<0.5\&\& rand2\geq 0.5 \end{cases}\tag{5}
ulg={xbs+randn×(MeanRule+randn×(xbsg−xa1g)),rand1<0.5&&rand2<0.5xrnd+randn×(MeanRule+randn×(v1×xbs−v2×xrnd)),rand1<0.5&&rand2≥0.5(5)
其中:
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x_{rnd}=ϕ\times x_{avg}+(1-ϕ)\times(ϕ\times x_{bt}+(1-ϕ)\times x_{bs})\tag{5.1}
xrnd=ϕ×xavg+(1−ϕ)×(ϕ×xbt+(1−ϕ)×xbs)(5.1)
x a v g = x a + x b + x c 3 (5.2) x_{avg}=\frac{x_a+x_b+x_c}{3} \tag{5.2} xavg=3xa+xb+xc(5.2)
其中,
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xbs组成的新解,这增加了所提出算法的随机性,以更好地在解空间中搜索;
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v_1=\begin{cases} 2\times rand,p>0.5\\ 1,p\leq 0.5 \end{cases} \tag{5.3}
v1={2×rand,p>0.51,p≤0.5(5.3)
v 2 = { r a n d , p > 0.5 1 , p ≤ 0.5 (5.4) v_2=\begin{cases} rand,p>0.5 \\ 1,p\leq0.5 \end{cases} \tag{5.4} v2={rand,p>0.51,p≤0.5(5.4)
算法流程图如下:
[1] Iman Ahmadianfar, Ali Asghar Heidari, Saeed Noshadian. INFO: An efficient optimization algorithm based on weighted mean of vectors[J]. Expert Systems With Applications, 2022, 195: 116516.